Realize that reverting to Tiger may not be simple. Some things may have been irrevocably updated to newer versions. Reverting usually involves wiping the internal drive, re-installing the system and then applications, then copying data files back on. If you're lucky you made clone backup from just before you installed Leopard and haven't changed much since then and can just turn back the clock.
...Of course, nobody wants to downgrade to a lesser OS. I'm suspicious that some (or even ONE) piece of software on my Mac is not living harmoniously with Leopard, or could it be a hardware element in my G5 that was made for Tiger and doesn't accept Leopard as well... Is there a way to check the compatibility of my G5 with all the software components I currently have loaded?
I have used Leopard on my 733 MHz G4s for several years without any serious difficulties.
There are no hardware incompatibilities.
It could be a portion of RAM which Tiger rarely used.
Unless you have a full backup of your Tiger install taken just before the upgrade it will be tedious going back.
You could spend weeks looking for the cause of your problem, which in my experience, is often the result of taking the 'easy' upgrade option rather than a full backup, erase disk and full install.
This my advice (I am not expecting all those here to agree with this):
1 - Backup the whole disk to an external disk with Carbon Copy Cloner - default options are probably OK for this
2 - Use Leopard installer DVD to erase the internal disk - splitting into 2 or more volumes can be useful - eg Tiger on one and Leopard on the other
3 - Install Leopard without importing any data or settings (except perhaps network preferences) during the install process
4 - Use Software update repeatedly until up to date
5 - Copy data (not system preferences or applications) from backup
6 - Reinstall third party software as required but check all for Leopard compatibility first
7 - Install AppleJack (it has a RAM check option) and use about once a month with the following command:
applejack AUTO shutdown
8 - The above command will repair the disk and permissions and clear caches - you should see AppleJack ReadMe for use of its RAM check
To eliminate RAM being the problem, Look at this link: Testing RAM @ http://guides.macrumors.com/Testing_RAM Then download & use Memtest & Ramber.
Do you have an Apple Hardware Test disc (the AHT is on the Install/Restore DVD that came with your Mac)? Running the Apple Hardware Test in Loop Mode is an excellent troubleshooting step for finding intermittent hardware problems. It is especially useful when troubleshooting intermittent kernel panics. If Loop Mode is supported by the version of the Apple Hardware Test you are using, you run the Extended Test in Loop Mode by pressing Control-L before starting the test. Looping On should appear in the right window. Then click the Extended Test button.The test will run continuously until a problem is found. If a problem is found, the test will cease to loop, indicating the problem it found. If the test fails, be sure to write down the exact message associated with the failure.In some cases, RAM problems did not show up until nearly 40 loops, so give it a good run.
The loop test sounds an excellent way to find intermittent RAM glitches especially if they are temperature dependent. I would certainly do this first if possible.
I think it is worth checking that all the RAM is identical (especially CL numbers) and meets Apple's requirements for this Mac. Some Macs are happy with generic RAM (eg PC 100) but some need RAM to Apple's special timing requirements. CL problems rarely cause malfunctions but do result in lost speed.
I will let it run overnight. See, for 4-5 days mow mu Mac has been behaving well, but it can suddenly go crazy for no apparent reason programs quitting, or hanging, The Finder can act up to a point I have to quit it.... This is beside the occasional night time crashes when I was finding my Mac's fans blowing and the red LED #7 glowing, which happened only after a restart. But I think I learned the trick, whenever I do a restart — I also zap the PRAM 3-4 times... So far it worked... so far...
For your help, guys. I will report next week.
OK, so I got "Apple Service Diagnostic Dual Boot" disc, v. 2.6.3 that fits my Late-2005 G5.
I ran it twice, once as a single loop (always "continue on error"), which took couple hours and PASSED. The 2nd time I put it to run for 5 hours. I checked the monitor from time to time, and all the "result" (?) lines in the Log were green. After about 5 hours I noticed LED #7 glowing again, and the screen was frozen, see below.
So at least I did not get any error messages...
The reality is this: As long as my Mac keep going for days w/o a restart, it's pretty stable. Once I have to restart, as long as I ZAP THE PRAM (3-4 times per restart), it will run OK.
I'll let you, guys, come up with your resolution....
All versions of OSX have serious issues, especially on PowerPC. Apple secretly gave up on the PPC long before they actually discontinued it. If you want a really good, stable, reliable OS, use Windows XP on a Pentium 4. I used to totally be a Mac person, but since Apple stopped producing real Macs in 2006, i.e. dropped their "Think different" slogan and started making PC clones (i.e. things w/ an Intel chip), I've gotten disgusted with Apple.
Btw, as i write this on my G4, my incredibly stable P4 running WinXP SP 3 is downloading videos and running an exhaustive phylogenetic analysis--all while its second hard drive sleeps peacefully. IMPOSSIBLE in any version of OSX. Thanks, Apple.
I have very few problem with either Leopard or Tiger on my 733 MHz G4s. Clearly these G4s are not as fast as my quad 3 GHz Intel based Ubuntu box but they are adequate for most of my modest requirements. I still use the G4s more than my Intel box but I will eventually move away from expensive hardware and OSs I have to pay for.