Excel security - I can't figure this one out

All,

I have a spreadsheet on a file server with a protected sheet. There are a
number of cells not locked on this sheet because I want the user to be able
to change these particular cells. (Until today, the sheet was not
protected at all, but the user totally fubar'ed some parts of the sheet by
not paying attention to what she was doing, so I locked the cells she
should not touch.)

Now, when opens the SS, she couldn't change _any_ of the cells, even those
that were not locked.

If I unprotected the sheet, she could change those cells, so I'm certain
the protection is what was causing the problem, but I didn't know why.

I access the SS via XP and Excel 2000. She accesses the SS via W2008
Server R2 (thin client RDP) and Excel 2003. Just for fun, _I_ signed on to
the W2008 Server and did the locking via Excel 2003.

Lo and behold, it now works. Learn something new each day.