Shaded out Unprotect Sheet...
 

Hi,
I've created a form in Excel 2007 which I have protected, that wasn't a
problem. However, when I protected my sheet I couldn't write in any of the
assigned texted boxes. I could choose from my drop down lists though. So I
was playing around with it to try and figure out why it wouldn't let me do
anything and I selected the option in Allow Changes by more than one user at
the same time by accident and I believe this may be the reason why I can't
Unprotect my Sheet now (which isn't availble to be selected in my ribbon like
it had been). I unchecked the "allow changes by more than one person..." and
click ok, my excel program crashes. It does this everytime. I am the only
user who has the work book open as well.

Can anyone help me?