> By "lock up", do you mean go into a non-responsive state? Also, to be clear - Excel is locking up, not just the VBE, right?
I also notice that you have MZ-Tools installed. Can you reproduce this with MZ-Tools disabled? How about with RD disabled and MZ-Tools enabled? If you have any other add-ins installed, I'd test them independently also.
If you could get a trace level log of this and post it here, that would be awesome.