1] Try lowering video acceleration under the Performance tab in Tools > Options in WMP.
If that doesn't work, try;
2] Downloading wmv codecs from Microsoft;
Select "Codec installation package" from the "Select download" pull down list.
or download and install the free DivX player from http://www.divx.com
This will install a different player and a codec pack that includes wmv codecs
See if any of that helps.
I just installed XP with SP2 on a friends computer.
Everything is ok but the windows media player. She can get wmv files through her e-mail ok and the sound plays but no video shows. I had her do a select all on the file types under tools and options, but still no luck. I even sent her back the file she sent me (which played fine on my computer) and still no go. Any suggestions?