|There is a Diagnostic function in Office 2007, |
do you still have the Diagnostic available in 2010?
If you do, would be curious to see what happens if you ran a Diagnostic while you have Yahoo IE open.
Might give you a pointer to where the problem is.
I would guess, it is either a Registry conflict or perhaps a DLL problem.
Another thing to try, is while Yahoo IE is open, try doing a Repair on Office.
That also might yield some clues.