I have a problem related to solver for which I discovered the same solution
independently. I can't open a particular spreadsheet that uses solver without
it crashing. (I have recreated the spreadsheet from scratch and the new one
also crashes.)

If after opening Excel I first remove Solver from the list of add-ins, then
put it back, I can open the spreadsheet without any problem.

This is with Excel 2007 in Vista. The spreadsheet loads a small table from
an Access database and runs solver from VB code for each record in the table.
Automatic calculation is off, so it shouldn't be doing anything when I open
it.