Help me troubleshoot my iMac | random SPOD and freezes

Question

ok, I am 1 step away from literally throwing this iMac out the window, but maybe someone has got an advice before I do so.
In the beginning of 2009, my iMac's harddrive went bad.
I was able to rescue everything via target mode so no big deal. I went and bought a new harddrive for it and replaced it myself. I found a very good guide for the whole procedure and after that I installed a fresh copy of OSX 10.4 on it.
Since then the system would start to do random freezes, sometimes for all running applications, and sometimes for just one or two simultaneously.
The freezes normally lasts between 10 seconds to 4 minutes and I have so far (1 year later) not been able to discover any kind of logic/pattern in these freezes.
Sometimes I can run a plethora of programs at the same time (iMovie, Photoshop, Quicktime, Safari, Pages etc) and everything goes fine for hours. Some times it will take me minutes to just launch Safari or Textmate.
Now, it isn't as though I haven't tried doing anything about it, it just that so far nothing have worked out.
Here is a list of things I have tried since it started in 2009
- Running Repair Permissions (Disk Utility or holding down SHIFT when booting)
- Running maintenance programs like Onyx, MacJanitor, Maintenance, iTools
- Fixing font issues using FontBook, LinoType and FontNuke
- Replacing/Upgrading RAM (I went from 1gb to 3gb)
- Testing RAM with memtest
- Running Disk Warrior
- Disabling various processes/services (spotlight/mds etc.)
- Uninstalling/upgrading/downgrading programs (mostly programs that I use alot like Firefox and Safari)
- Upgrading the OS (first to Leopard, and then to Snow Leopard)
- Re-installing OS X (I have tried different combinations like re-installing to Tiger, then upgrading to Leopard and SL, re-installing to Leopard without upgrading etc.)
There might be more but I really cannot remember.
Of course my focus has been mainly on the harddrive itself since this was the piece that got replaced, but everytime I run Disk Warrior or Onyx or any other diagnostics app I have come across, I am told that the harddrive is doing fine.
In the middle of 2009 I then created a 50gb partition on which I installed Win XP. This was because of some work related software that I needed to run. Now, on Win XP I have yet to experience any problems relating to the one I have on OSX. (Of course there are problems with Win XP, but none of them were relating to my specific issue here).
So as it is right now, and have been for too long, I'm better off running Win XP than I am running SL, and that just ****** me off..!
Does anyone here have an idea about what to do next?
I have thought about buying a new harddrive to replace the initial replacement drive, but if that is the only choice I have left, I would rather save up for a new iMac instead.
I have already spent more than enough trying to fix this one.
Here are some details about the system:
Model-id: iMac5,1
Processor name: Intel Core 2 Duo
Processor speed: 2.16 GHz
Processors: 1
Cores: 2
L2-buffer: 4 MB
Memory: 3 GB
Bus speed: 667 MHz
Boot ROM-version: IM51.0090.B09
SMC Version: 1.9f4
OS Version: 10.6.2
Some of these are roughly translated by me from Danish.
Thanks to the people still reading this.
.cb

Answer 1

Hi Kguy,
Thank you for the reply.
The freezes happens when opening programs and when running them. And it happens with (as far as I know) all programs on the computer (including TimeMachine, Dashboard apps, Finder, login in/logging out etc.)
As far as I know this is not related to my network, but I will try you suggestion and disconnect the computer fully before running programs on the computer.
Sometimes when the freezes happen, everything on the computer freezes, even the seconds on the clock.
And if I am watching something in Quicktime/VLC/DivX and a freeze happens. After the freeze is over Quicktime will then resume x amount of time later in the movie. Where x is equal to the amount of time the froze lasted.
Hope this helps clarifying
cb