I also have the same problem on Windows XP thats why I reverted to Windows 2000. However heres what ATI suggests on the problem.
http://www.ati.com/support/infobase/3940.html
There is a beta ATI Multimedia Center v7.6 in the ATI website.
http://www.ati.com/support/drivers/misc/mmc7-6b-tvwonder.html
I havent tried those yet but that might solve that problem. If try it out please give me feedback so I could make use of it also.