Add Another Person to the List I'm having the same screen problem as anyone else. For me, it started when I upgraded to 10.5.3. I was rock solid before that. MacBook Pro 15" OS X 10.5.3 Parallels Build 5600 XP SP2 Guest OS (transported from a work laptop) The only slight difference for me is that I run two virtual machines (not at the same time), i.e. one for work stuff and one for home stuff. My "home" XP virtual machine is working flawlessly as usual with no screen problems. It's only my "work" virtual computer that has the flickering issue. Very odd. BTW, thanks to the poster who mentioned this issue goes away in full screen mode. Luckily, I run multiple monitors and so for me, I can get around this by giving Parallels its own screen.