It could be the drivers or the wmv codec. Can you provide a few more details?
What graphics card do you have and which version of Catalyst did you download?
Did you have the same problem with the previous version?
Did you uninstall the old Catalyst before installing the newer version?
Do you only have this problem with wmv or is it all video formats?
Sorry for all the questions, but it helps narrow down the possible cause.
Try installing this free codec pack (the full 2.49 version), reboot and see what happens.
http://www.free-codecs.com/K_Lite_Co...k_download.htm