Eh, what a stupid problem. It appears that QuickTime has problems with NVIDIA's Digital Vibrance (feature that makes colors more vibrant and rich).
Mac, can you report this incompatibility to Apple?
I'm using NVIDIA GeForce 6600GT 128MB with drivers ForceWare 81.98 (WinXP 32bit) on Windows XP SP2 system. QuickTime is version 7.0.4.80.