strange blincks of video in vlc

[buzz]

hello,
maybe there is allready such topic with the seme problem here but i couldn't find it. sorry if it's so...

but i have a really stange problem while playing any video in vlc.
quite often (20-40 seconds) the image in vlc make strangely blincks. like when its changing the brightness 10 times per second. this is very annoying. may be the problem is in incorrect setup.
running vlc on winxp x64. nvidia 7900gs video, 2gb consair xms 2, x2 4600+ amd..

thanks