Hi Dominik
I'm struggling to work out exactly how we fixed this issue. However, the following would be worth checking:
1. Check the user is not running a 64bit version of IE (unless you have the BIG VOLUME version of EPM installed)
2. Check the correct version of IE is installed based on your service pack compatibility
3. Try deleting the EPM cache.
Let me know if none of them fix the problem and I will dig a little deeper into my archives.
Ian