Vista - Windows pop-up when I "x" to close a program

When happens most on MS Office programs but have had it happen on others.
When I "x" to close, for example PowerPoint, I get a pop-up message that reads:
"Microsoft Windows"
"Microsoft Office PowerPoint has stopped working"
"Windows is checking for a solution to the problem..."

Sometimes it will automatically restart.

Anyone encounter this and can offer suggestions?

Thanks

Does it do the samething when you file exit.

A few more details.
At first I thought it was only when I modified a document but that doesn't seem to matter.
It does the same thing when I "File", "Exit".
It doesn't do it consistently but more than not.
The program it happens most with is PowerPoint 2007 but recently I've been using that more than any other.
I tried to upload a couple of attachments which are .jpg screen captures of the two most common messages I get.
I'm net at this so I don't know exactly where they went.



Regards,

Have you tried saving before exiting or you already saved and closing powerpoint.

I've done it most of the ways you might think of:
Saving first or not, just open a document, do nothing but just "x" out, it occurs in all those cases.

Regards,

I am having this exact same problem. I started a new topic but no responses. Has anyone found a fix for this yet?

Thanks

Some addon may cause this problem.

In run type the following powerpnt /safe, now the power point will open in safe mode.

Now try to close power point.

Let me know the result.