Vegas: Strange Video Disturbance

[Photek75]

Hi all,

i need your help with a strange disturbance i have in Vegas 8. As you can see on the screenshot i get this weird flickering while doing a crossover.

Even stranger though, i did not have this problem on the Computer i created the .veg file in the first place (crap business PC at work). This flickering does also not happen on all crossovers, only on some.
I tried with the same video files in a new project, cut them in a different way -> same result. I deleted the original .sfk files so my computer created them anew, i cut off some frames of both affected to make sure it's not the source videos. The crossover is a simple drag&drop, no special FX added; with FX added it's the same...

Just in case you think this is a Vegas preview bug or something: after the render process this flickering is clearly visible !
I appreciate your help/tips/recommendations. Thank you !

PC Details: GeForce 8800GTX, regular NVIDIA Drivers, XP SP2 etc..