I haven't seen this one before:
I have just upgraded my MB to an Asus A7V133. Everything seems to work, except that JPG pictures are "scrambled" (that's the only way I know how to phrase it - the image has funky colors all over the place and the image is unrecognizable). Also, cut-scenes in Dark Reign 2 have white verital lines all over the place...
The video card is an AGP Voodoo3, but I have taken it out, and tried a Matrox Millenium card (regular PCI card), and got the same results! So, I don't think it is an AGP setting problem.
The only reason that I think this isn't a MB problem is because I recently got an Azza Motherboard and had to return it because of memory problems. I used the same CPU on it (an Athlon 1G), and had the same problem.
Have you looked at the AGP memory setting in your BIOS. Sometimes there are options that list 16 MB, 64 MB...256 MB, etc. If the setting is too high (more memory than your system has), problems can occur.
Just an idea.
That's the strange part. I took out the AGP card, and put in a regular PCI video card. Got same problem.
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This may be a stupid question, but I'll ask it anyway. What is your OS configured at for resolution and colors? I have seen what could be interpreted as "scrambling" of images when the resolution is too low or the number of colors is too low.
Also, I know you tried this with PCI and AGP, but remember to select the primary video card type in addition to the memory settings when you switch between AGP and PCI. You would be amazed the difference it can make.