I know, brother bear. If it's killing a program called (but not necessarily) regedit.exe in normal mode, I'd bet that it's a virus. The virus doesn't get started in Safe Mode, so that's why it doesn't affect regedit or taskmgr there.
Download Process Explorer for Windows v11.0 from Microsoft's website. Run it, and select the Image Path column (from View... Select Columns).
What I think you should do is start killing processes, one by one, and running regedit. The process that killing allows regedit to run is the guilty party. Start by killing everything outside of C:\WINDOWS. Even if you're sure the process isn't a virus, kill it anyway.
Any process that immediately restarts after you kill it is also a prime suspect. Make a note of that process name and path. Let me know how you get on.