We currently use several macro driven workbooks. The problem we have
recently encountered is that some users are experiencing fatal errors when
having more than one of these workbooks open.

For instance:
I open WorkbookA.xls and enable macros, select a couple validations, run a
query, look at my results. I then open WorkbookB.xls and do the same thing
but now I get a fatal error or I go to close one of the workbooks and get the
fatal error. Anyone have any idea as to what the problem may be? One of the
errors I have seen is: Excel is encountering a problem and needs to close . .
.. .