since lisod ihatag suggestions kai wala man ka nihatag sa imo system/hardware info, i suggest this:
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if u just recently updated your drivers, download/install DriverCleaner or DriverSweeper.
remove all nvidia/ati drivers from Add/Remove Programs.
boot into safe mode and use DriverCleaner/DriverSweeper to remove left over driver files and registry entries.
Boot Windows. Install your videocard drivers. Reboot and test....
if the same gihapon, do this:
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remove all codecs installed.
download Combined Community Codec Pack from:
CCCP - Combined Community Codec Pack and install.
This codec has best in my WinXP system to play any media files(.ogm,divx/xvid,avi,mkv, DVD etc etc etc)
You may also try VLC...
if mao gihapon imo problema, aw ambot lang. nid to personally check your system...
Hope this helps...