Why does the VBA Editor open on its own sometimes?
As stated in, Microsoft Support Center:
"This problem occurs only if the Microsoft Visual Basic Editor window is maximized."
Solution:
Un-Maximize Visual Basic Editor and close it.
And you are done!
If you have previously set breakpoints, it may be that you still have a phantom breakpoint. Try choosing "remove all breakpoints" and see if that clears the problem.
Check also that you have not chosen "Break on all errors" under options, and that your error handler is functioning properly.
Believe it or not, this is a known issue. Check out this MS Support link:
http://support.microsoft.com/kb/829059
I have the same problem and found it while I was looking for a solution. Since it gives no advice, I kept searching and came across your post. I will come back with an update if I find a solution.