New driver 331, video playback problem 60/24Hz

I updated my video driver with 331 version. I have problem with video playback now. In 60 Hz mode it is not smooth as it should be. But the real problem is 24 Hz playback - after several minutes it starting to skip frames, for a few seconds, not one frame, but many. I tried everything, but the playback is not getting better.
I have tried to roll back to previous driver 304, but Nvidia control cannot change the refresh rate to 24Hz.
I know that it is normal to skip a frame every 200 s or so, but this is not the case. It stuttered for a few seconds every several minutes.
With the new driver 331 XBMC cannot play 24Hz material, it gets frozen.
My card it GT630.
Any advice?
Best regards,
Encho Naydenov

Plz provide reproduction steps in detail and nvidia bug report ? Any previous driver worked for you ?