JamesvonPC,

The best way to make sure it is working, do a clean install of WinXp.
Note : sp1 or sp2 with all latest updates doesn't prevent drmdbg to work properly. Remember only if you install update KB891122, it will prevent drmdbg to work.

At the first time you play any protected content after clean install, wmp will connect to internet for individualization or security upgrade. Let it do it, then verify that IndivBox.key version in your C:\Documents and Settings\All Users\DRM is 10.0.0.3646. Only this version of IndivBox.key will work perfectly to undrm protected media in my knowledge. If you found IndivBox.key version 3930, drmdbg will not work anymore.

Some of content provider of drm media will ask you to install KB891122 before you can play the media. If this happen, you can't undrm the media anymore.

Ok, best luck

download wmp 10.0.0.3646 here:
http://download.microsoft.com/downlo...e1/mpsetup.cab
remember to extract the .cab