It would seem that there is some odd conflict with WMDC and the printer driver, but that's only speculation on my part. Basically, this should not be happening. I recommend that you contact support.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare Forum Moderator