I'm having the same problem. Mine seems to be related to some add-ins that
we're using. Disable the add-ins and everything works fine. These add-ins
work fine under other versions of Excel, and don't fail on every machine in
our office, though they're all at the same patch level & configuration. I'm
guessing it's some sort of race condition bug introduced in Excel 2007.
Still digging to see if anyone has an answer.