RebellionRob: Yeah i'm getting the same thing.
Heres the message if anyone can help out.
Unfortunately the message is vague and tells little. Have you tried uninstalling the game, clearing out (manually deleting) all remaining files and Witcher 2 registry entries and tried reinstalling the game and applying the patch immediately after install? Many have report this works in the majority of patch installs, although this patch is apparently not perfect. I'd call this a beta patch, but most cases haven't had the error you've listed. Also, you may want to disable the UAC (User access control) which is reported to cause problems in general with the Witcher 2 installs.