From the info so far, I can see no reason for it not to install.
Give it another go, erasing Macintosh HD first to ensure any files that did get installed can't interfere (no need for zeros).
If that fails, restart holding down the mouse button to eject the DVD (Note - if it's a bluetooth keyboard, wait for the chime before holding down the mouse button).
Clean the DVD carefully with a lint-free cloth (the microfibre ones given away with spectacles are good) wiping from centre to edge (not circularly).
Then try again. I'll try to do some research in the meantime, but maybe X423424X can recall similar problems.
Especially because this is a used iMac, it would be a good idea to run the Apple Hardware Test (AHT) for it to see if it turns up any hardware problems. If this is in fact a "late 2009" iMac AHT should be on the "Applications Install Disc 2" disc, one of two system discs that (hopefully) came with the iMac.
I don't have a late 2009 model to check, but usually the AHT version is printed on the disc. If yours is a 27" 2009 model, it should be version 3A202; if the 21.5" model, it should be version 3A176 (according to the Mactracker database).
AHT is model specific; IOW, you must use the version meant for your iMac.
Any progress bartonfive?
I've been scouring a few threads and one thing keeps coming up as a solution with that message - bad RAM.
Many of the cases were fixed by replacing RAM (or just removing one stick if there are two in there).
Follow R C-R's advice and run AHT - to do so, insert disc 2 and start with the D key held down. Run it in Extended Mode at least three times (it will take quite a while).
Unfortunately, no. My computer only came with one disc so I'm beginning to question if I was even given the correct software. I tried running AHT by using my one disc and holding down "D", but nothing happens.
I'm starting to think I may have to take my iMac in to have someone look at it. Question: can I upgrade to Lion now or does the computer have to have a fully functional Snow leopard in order to install?
Hardware test is only on disc 2 "Applications Install Disk", which also contains the bundled iLife apps. You should have been given both discs - it's a licence condition that the discs are part of the computer bundle.
If you have any doubts about the OS install disc, can you check the other identifiers I mentioned earlier - usually under the stand base, and let us know so we can attempt to cross-check.
In order to get Lion, you need OS X 10.6.6 or later to access the Mac App Store and purchase Lion as a download (fast broadband connection needed). Alternatively, it's available on a USB stick from the Apple Online Store for $69 ($29 for the download).
You probably could load Lion directly with the USB stick, but it would be wise to check there's not a RAM issue beforehand, as that could just as easily screw up a Lion install as a Snow Leopard one.
The RAM's not difficult to get at, so shout if you want to try that.
Thanks. Is checking for bad RAM just a matter of removing it and them adding it back to see if it malfunctions?
That's one way to do it, assuming you have two or more modules & removing one won't leave you with less RAM than the minimum needed to run the OS.
Another way is with Rember. Substitution with known good modules is the best way but Rember does a pretty good job of detecting most RAM problems if you run it in loop mode for several hours.
Right - here's a how-to for removing and replacng the RAM.
Remove one stick, plug the Mac back in and try the installer again. If it still doesn't work, refit that stick and remove the other and try again.
Note - when refitting the RAM, ensure it's square to the slot, and press firmly all the way until you feel a sort of soft click. It can take more force than you expect.
Success!! I pulled all but the left front (closest to the screen) slot and was able to load the OS onto my computer. Now two questions:
1) Should I try reinstalling the other 3 DIMMs and restarting to see if they are bad (or just needed to be reset)?
2) I can get sound when I open the sound in System Prefs, but when I try to adjust sound from my keyboard it dims the screen when I hit mute, nothing for sound decrease and brings up the Dashboard when I hit increase. Any idea why it would do this? Thanks.
Reinsert them one at a time and check for adverse effects. If you manage to get all 4 back in without apparent problem, follow R C-R's link and download Rember. That checks RAM specifically and will tell you which if any is on the verge of failure.
As for the keyboard, that sounds like a recent new keyboard on a slightly older Mac. Before getting worried, update the OS to 10.6.8 via the Combo Installer. The latest keyboard should work correctly with that.
Thanks again! Keyboard issue resolved.
I first booted with only one DIMM in the top left slot (Bank 0 DIMM 0) and ran Rember with no issues. I inserted all four DIMMs and got a "Failure! Data mismatch @ local address 0x00000001adf89040" (actual data: 0x0000000ade89040). Similar message with DIMMS in Bank 0 DIMM 0 and Bank 1 DIMM 0. Now I am running multiple permutations to see if I can narrow it down to which one; I have it testing with DIMMs in the top and bottom slots left side and the test is taking forever, not so wiht the other tests.