Are you trying to mod MAIN or just doing scripts in a normal standalone mod?
When you import a script it will in my experience always throw the errors you described. A restart of the editor has always fixed this for me.
Those errors can be caused by other things though, one of which is NPCs moving between instanced areas via charscript.
If you are modding MAIN I can't be of much help but if it's a standalone mod, you can upload your work and I can try and find out what's broken tomorrow.
Far as reinstalling goes, if you are going to try that I'd also reinstall D:OS as well, not just the editor. I have had my MAIN get corrupted a few times and had to do this.
