Cannot Install Updates Internet Security 2009 And Windows Xp Home

I have had a problem with Internet Security 2009 and Windows Xp Home. I can simply not install an update using the "Update Now" feature.

I have tried everything, completely uninstalling IS2009 (using the tool Bitdefender provides), reinstalling Windows, deleted several files and so on, tried about 50 times now to update, it is downloading fine, and get the "Update Completed", but nothing is installed, have to manually download the weekly.exe to get updates, and even though I have installed the latest, there is still about 20MB updates available when using the built in update service.

What is wrong? I have about 180 days left...?