This just started happening to me: new columns added to an excel workbook
are locked (the checkbox on the "Protection" tab of Format Cells is checked).
I tried creating an entirely new workbook, and all the cells in it were
locked.
What could be happening?

Helpful information: I just installed windows 7 RC, and along with it
Office 2007 Enterprise Edition SP2 (build 6425). I suspect that the problem
is related. I did not have this problem previously, when I was using Office
2007 SP2 with Vista.