Help with possible mother board issues, Hard problem to solve

I'll start with my machine specs:
Abit AV8 3rd eye mobo
1 gb Crucial Ballistix DDR4 ram (2x512, dual chanel)
Enermax EG465p-VE 460W power supply
VIA 3500+ Athlon
2 SATA harddrives
1 IDE Harddrive
1 3.5" floppy
1 DVD ROM
1 DVD Burner
1 SCSI DAT tape drive
1 NVidia AGP card
1 Appian PCI video card
Windows XP 32 bit SP3
Latest drivers, latest updates, etc.
latest bios
No over clocking.
All unnecessary services stopped.

The problem has manifested itself in the most annoying way. The most obvious symptom is when every I open an Adobe CS2 product(legal) (Photoshop, Illustrator, Acrobat), I get an error that says "The license configuration data for Adobe Creative Suite is no longer usable". I re activate it and some times it works, sometimes is says "An attempt was made to load a program with an incorrect format". the software doesn't exactly stop responding at that point... I can click things and it acts like it too the command, but it just sits there. For example I can click the file menu, and exit, but it doesn't exit it just returns me to the work space. Forcing and end task kills it. There are also other random problems such as Word, Excel, Outlook, firefox crashing. I uses those programs mostly so that is why I say those. Also, Prime 95 usually crashes or fails with this error: "FATAL ERROR: Rounding was 0.484375, expected less than 0.4
Hardware failure detected, consult stress.txt file.
Torture Test ran 2 hours, 18 minutes 7 seconds - 1 errors, 0 warnings.
Execution halted."
Prior to this problem occurring this machine was very stable. Unfortunately there have been no hardware or software changes that coincide with this problem occurring.

So, this problem has been going on for 6 months. It is a complete pain in the butt. I have done everything I can think to test it. I have searched this forum, google, and other for testing methods. What I have done so far is this:
-Ran Memtext86, memtest86+, winmemtest (MS) and one other memory tested for at least 10 hours each-- no errors
-Virus, malware, spyware scan AVG, various other scanners mentioned here-- nothing found
-Clean reinstall of Xp on another drive -- no change
-Disk error checking found no problems, Smart reports no errors.
-Tested power supply with a multimeter. The 5 volt lines were 5.08v-5.09V, the 3.3v lines were 3.36v-3.38v, the 12 volt lines were 12.14-12.16V. This was tested with the machine under load, running a disk check, a defrag, a prime95 test and a virus scan all at once. The values came from both the mother board ATX 20 pin and 4 pin connecector as well as the various molex plugs.
-Replaced the CPU with a new one -- no change
-Several different installs of XP, no updates, all up dates, different drives, etc.

The CPU temp is fine and I see no other problems.

This leads me to think the mother board is faulty.

I have a back ground in IT support and this is the second problem that has stumped me.

Opinions? Ideas?

-Chris