I am having a problem with playing video files

[Siddhartha]

When I play a video file, avi, mpg, wmv, etc. using Windows Media Player, the video portion plays for a second or two, freezes for a couple of seconds and then starts playing again. The audio part of the file continues playing while the video portion is frozen. When the video portion unfreezes, it speeds up until it catches up with the audio part of the file.

My system:
WinME
AMD XP1900+\MSI K7T266 Pro2
512 meg 2100 DDR ram
Voodoo 3 - 2000+
SB Live MP3+

Any help would be appreciated.

TIA

Randolph