black video and slow music

Archived from groups: microsoft.public.windowsxp.video (More info?)

Since installing WindowsPack2, neither music nor videoclips playing directly
from web have not been being played properly. Music is slow and video black.
The internet connection is in order, casual web pages open without problems.
I use antivirus program Nod32. Can anybody give me some hints where the
problem may lay? Thanks ahead.