Tell us please a little bit more about your system: How much RAM do you have, your processor, free space on your hard drive. With Lion you need more RAM than with Snowleopard to run Aperture properly.
And can you post a log from the crash report? The first 50 lines should suffice.
Do you have any plug-ins installed?
If you had any plug-ins you would probably remember installing them. I.e. the Nik plug-ins have been causing crashes on iMacs with Lion. If you have any Aperture plug-ins they would be installed either in
- your user Library: /Users/your user name/Library/Application Support/Aperture/Plug-Ins/
- the system Library: /Library/Application Support/Aperture/Plug-Ins/
Do you know how to show the hidden Libraries in Lion?
Your free space on the hard drive seems to be sufficient, but the RAM may be a problem. When I upgraded to Lion I had exactly the same situation - Aperture was doing just fine with 4 GB RAM on SL, but on Lion it was continually swapping pages out, because of insufficient RAM.
To check if RAM is the problem, start the Activity Monitor from Applications -> Utilities and click the heading of the column "Real Mem" to sort the processes by memory usage. You will notice, that most of the time Aperture will be at the top of this column, even when doing nothing. Also Safari will be using nearly 1 GB of RAM for its caches and Mail half a GB. If RAM is an issue, it is a good idea to quit these apps when running Aperture.
When Aperture seems to stall, look at the disk writes. If you get plenty of disk writes in that situation, it would be a sure sign that additional RAM will help.
Did you upgrade to the latest Aperture version 3.2.2?
P.S. if Aperture crashes again, post the crash log; there have been some problems with Lion and Aperture on iMacs, and a log woud help to narrow down the problem.
I had a look at the memory usage in the activity monitor, during me playing with Aperture (and I didnt do much, yet the beachball always came up whenever I did anything) the real mem never went over 500mb, I do have something called report crash that seemed to be 2nd or 3rd though. The 2nd biggest item never went over 200mb.
What do make of this?
Edit: Aperture just crashed, how do I post the report, do I need to delete anything that should not be broadcast on the net?
sorry, I could not get back to you earlier - there was an interruption by Apple maintainance.
How to post the crash report:
In the Console Window is a left column with Diagnostic and User information. Select the most recent Aperture Crash and then copy the text of the first 50 lines or so to the clipboard and past it into your post. I don't think these lines contain access information to your machine, but we will see the frameworks installed used by Aperture, and that may be helpful.
Process: Aperture 
Version: 3.2.2 (3.2.2)
Build Info: Aperture-201095000000000~4
Code Type: X86-64 (Native)
Parent Process: launchd 
Date/Time: 2012-01-01 09:33:05.776 +0000
OS Version: Mac OS X 10.7.2 (11C74)
Report Version: 9
Sleep/Wake UUID: 4B7A42CE-953D-4210-8C17-22B9C45E11C5
Interval Since Last Report: 870365 sec
Crashes Since Last Report: 3903
Per-App Interval Since Last Report: 701449 sec
Per-App Crashes Since Last Report: 7
Anonymous UUID: FCF2D2E5-4713-4063-9614-F2A2CE7C94B1
Crashed Thread: 45
Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
objc: garbage collection is OFF
Thread 0:: Dispatch queue: com.apple.main-thread
0 com.apple.CoreFoundation 0x00007fff917c3bb2 DYLD-STUB$$object_getIndexedIvars + 0
1 com.apple.CoreFoundation 0x00007fff916b0d64 -[__NSArrayI dealloc] + 148
2 com.apple.AppKit 0x00007fff8eda3dd8 -[NSView(NSInternal) _updateTrackingAreas] + 1336
3 com.apple.CoreFoundation 0x00007fff916ff01e __NSArrayEnumerate + 718
4 com.apple.AppKit 0x00007fff8eda3dc8 -[NSView(NSInternal) _updateTrackingAreas] + 1320
5 com.apple.AppKit 0x00007fff8eda3e77 -[NSScrollView _updateTrackingAreas] + 114
6 com.apple.CoreFoundation 0x00007fff916ff01e __NSArrayEnumerate + 718
7 com.apple.AppKit 0x00007fff8eda3dc8 -[NSView(NSInternal) _updateTrackingAreas] + 1320
8 com.apple.CoreFoundation 0x00007fff916ff01e __NSArrayEnumerate + 718
9 com.apple.AppKit 0x00007fff8eda3dc8 -[NSView(NSInternal) _updateTrackingAreas] + 1320
10 com.apple.CoreFoundation 0x00007fff916ff01e __NSArrayEnumerate + 718
11 com.apple.AppKit 0x00007fff8eda3dc8 -[NSView(NSInternal) _updateTrackingAreas] + 1320
12 com.apple.CoreFoundation 0x00007fff916ff01e __NSArrayEnumerate + 718
13 com.apple.AppKit 0x00007fff8eda3dc8 -[NSView(NSInternal) _updateTrackingAreas] + 1320
14 com.apple.AppKit 0x00007fff8eda3720 __-[NSWindow _postInvalidCursorRects]_block_invoke_1 + 1107
15 com.apple.CoreFoundation 0x00007fff916c6f37 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
16 com.apple.CoreFoundation 0x00007fff916c6e96 __CFRunLoopDoObservers + 374
17 com.apple.CoreFoundation 0x00007fff9169c159 __CFRunLoopRun + 825
18 com.apple.CoreFoundation 0x00007fff9169bae6 CFRunLoopRunSpecific + 230
19 com.apple.HIToolbox 0x00007fff900d83d3 RunCurrentEventLoopInMode + 277
20 com.apple.HIToolbox 0x00007fff900df63d ReceiveNextEventCommon + 355
21 com.apple.HIToolbox 0x00007fff900df4ca BlockUntilNextEventMatchingListInMode + 62
22 com.apple.AppKit 0x00007fff8ecdc3f1 _DPSNextEvent + 659
23 com.apple.AppKit 0x00007fff8ecdbcf5 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 135
24 com.apple.Aperture 0x00000001004b284b 0x100000000 + 4925515
25 com.apple.AppKit 0x00007fff8ecd862d -[NSApplication run] + 470
26 com.apple.prokit 0x00000001013673c6 NSProApplicationMain + 387
27 com.apple.Aperture 0x000000010000f454 0x100000000 + 62548
28 com.apple.Aperture 0x000000010000f214 0x100000000 + 61972
Thread 1:: Dispatch queue: com.apple.libdispatch-manager
the part where Aperture crashed is typical for crashes caused by contextual menu items. Where you by any chance right-clicking or ctrl-clicking when the crash occurs? Do you have contextual menues installed, e.g. iView?
P.S. I'd remove all traces of Haxies , Application Enhancer, Fruit menu etc., if you have them installed. Dectivating the haxies did bring my Mac back to normal when I switched to Lion.
And since the the program crashed using the com.apple.HIToolbox Framework, it may help to remove the propertylist /Library/Preferences/com.apple.HIToolbox.plist from the System Library.
The last time it crashed I was actually in safari, aperture was open at the time behind the safari window.
what do you mean by iview? or contextual menus.
All I am in at the moment is the viewer screen, with the split view just trying to look at photos, but it is so slow that I cant even do this!
Did the error log mean anything?
what do you mean by iview? or contextual menus.
That are little helpers that you install that give you menus when you right-click. These menus change, depending on the context you are in, and generally are very useful. But some of those, i.e. the haxies I mentioned above, tweak the system in risky ways, so you have to remember you installed them when you upgrade the system. You find those additional helpers in
~/Library/Contextual Menu Items/ or /Library/Contextual Menu Items/ if you have them installed.
iView is a Photo editor plug-in, that also caused such crashes previously.
The crash report you have, is very typical for a crash caused by these plug-ins. But if you have to ask, what the are, you probaby very wisely refrained from installing those. Otherwise I do not see anything specific in your crash report.
Is it really only Aperture that is crashing? Then I would try if the general basic Troubleshooting measures help; they will be useful if you have a corrupted Aperture Library or faulty preferences.
Aperture 3: Troubleshooting Basics: http://support.apple.com/kb/HT3805
Also, if you have not done so, run a hardware check to make sure your disk and RAM are o.k.:
Using Apple Hardware Test: http://support.apple.com/kb/HT1509
OS versions and app versions usually evolve to use more RAM and system resources as RAM gets cheaper and hardware gets stronger. Basic tech evolution, a good thing. 10.7 typically does require more RAM than 10.6.
Drives slow as they fill so verify that all hard drives are no more than approximately 70% full as a guideline. Even less full is better. Your 500 drive now filled to 380 has been slowing since it was at 200 or so. Your system operation is being slowed by the overfilled internal hard drive.
Even if RAM is not the specific cause of a given anomaly having extra RAM overhead often does seem to facilitate smoother operation. When RAM was expensive designers and users both learned to minimize RAM but with RAM cheap it is illogical to work to minimal RAM amounts.
Add RAM. 4 GB is marginal in 2012 with cheap RAM available.
You can evaluate whether or not you have adequate RAM by looking at the Page Outs number under System Memory on the Activity Monitor app before starting a typical work session; recheck after working and if the page outs change (manual calculation of ending page outs number minus starting page outs number) is not zero your workflow is RAM-starved. Ignore page ins, the pie charts and other info in Activity Monitor.
If your test shows that page outs increase at all during operation it is affecting performance. You can
• add RAM as feasible
• and/or simply try to run only one app at a time, for sure diligently closing unneeded apps like browsers
• and/or switch 64-bit operation to 32-bit operation (which will make some additional RAM space available). Note that your Mac may already default to 32-bit. See Switching Kernels:
Note that RAM is cheap and heavy apps' usage of more RAM is a good thing.