Excel functions not available then program stops
 

Hi -- I hope someone can help me! I'm using Excel 2007 on Vista. I first
started using this in April 2009, and from the start, the 'Insert' tab at the
top has never been functional. Whenever I've clicked on it, it's disabled
any other functions and resulted in me having to restart the program.

Now, however, this is happening with EVERY function except the basic
functions under 'Home' -- can't access anything in 'Data', 'Formulas', etc.
along with 'Insert.' Whenever I click on one of these tabs, I have the same
problem -- won't open, makes all other functions non-responsive.

The application itself doesn't crash. I can still move around the cells in
the worksheet I'm working on, but it no longer works in any effective way. I
also can't 'Save' the file after this happens; I have to just force it to
close and restart.

This is really getting tough -- I have a lot of data to sort through and
need help ASAP. No one in my company has any idea what is going on.

I'd be grateful for ANY suggestions!