I have also have this problem, new PC and office 2007 on vista. Mine tends to
happen frequently, 3 out of 4 times I would estimate. It's incredibly
annoying especially since I use excel frequently.

If Microsoft know of this issue perhaps they could provide an update on
progress for resolving this or at least some background on the cause of this
problem or at least a probem number so that we can track it.

Any more news on this?