Could it be that GC2 uses the TSC as timer (via RDTSC or whatever)? Until today, I got strange behaviour from time to time with planets spinning too fast in overview windows, but today I activated Cool'n'Quiet and it's all too fast. Edge scrolling takes me beyond the limits of the map (I've been at coordinates like 59000:something!), planets are a blur and the ship preview in the "new game" dialogs is also just a wee bit too fast (meaning that it's about 20 ships in all directions flickering over each other...)
This seems to be pretty much the problem that has been solved in Serious Sam 2 with the latest patch, in which apparently the whole system was switched over from RDTSC to QueryPerformanceTimer.
http://support.microsoft.com/?id=896256
http://blogs.msdn.com/tparks/archive/2005/05/14/417516.aspx
http://forums.seriouszone.com/showpost.php?p=688033&postcount=139
Please get this fixed in the Beta... Pretty please?
(edit) perhaps I should mention this: CPU is an AMD Athlon X2 4200+