Hi benja,
When you uninstall Word/Office, it leaves behind numerous registry entries and all the user fiels, so any problems related to those will remain.
Try the approaches suggested here:
http://support.microsoft.com/kb/921541
http://lounge.windowssecrets.com/ind...owtopic=197827 and
http://word.mvps.org/FAQs/AppErrors/...artingWord.htm
for various series of troubleshooting steps that will help you track down (and hopefully solve) the problem.