Thanks all for help - I've solved the problem.

The solution was:
- repairing VS 2003
- restarting
- repairing VS 2005
- restarting
- everything is fine again ;-)

>Hi all!
>
>I've Visual Studio 2003 and 2005 installed on one machine and now I'm encountering a very odd problem.
>When adding items to the toolbox I receive the message in the '.NET Framework Components' page: Error Loading Property Page
>
>Repairing the installation, restarting, ... didn't do the job.
>
>Any suggestions?
>TIA