Thanks for the hint. I actually read this before and tried the reset option even though it didn't feel like my windows are gone. They were actually never there 
Anyway, I tried and deleted the nwn toolset-folder at local settings but to no avail.
Well, I am from Germany and my OC Game and my MotB Version is german. My SoZ is a CD from the UK. The only difference between the different CDs seems to be that if it comes to the german CDs I have the option to install the game in german, of course, as well as in english. I chose english though for all of them. I patched it all the way up with english patches. I am not sure if this might cause an issue.
Edit: And I have the game installed at the root directory not in progam files (x86). Not sure if this makes a difference.
I am using Win XP 64-bit.
By the way, I can play the game with no problems at all. So everything seems alright. Just when I wanted to pick up creating stuff on my own again I am missing those tabs where I can have all the convos and areas listed. Only thing shown is the list for scripts.
Any further ideas are much appreciated. I don't really feel like installing it all over again with the same result in the end.
Thanks in advance again.