Wow. This is awful. The last time I did a project using these same files was with an earlier version of PD7, back in November of 2008. Maybe this is a regression issue, because now I'm having similar problems. I have to say, this kind of error, being this prevalent, seems like amateur hour.
I am trying to split an mpg file that was originally several minutes long. After splitting, it seems able to play, once, from that point in the editor, but any kind of manipulation (just attempting to skip forward in the track or split again, for instance) and the sound is completely out of wack. I can't even tell by how much.
Increase virtual memory? Try changing to 1024x768? Maybe you were hitting level 1 tech support or something and they were just giving you the list, but seriously? If that's all they got for you, I'm sorely disappointed. These are reproducible testcases made with clips of video in common formats created with commercial home camcorders.