Just to add to AJW's response.
You can verify that it is a macro by starting excel in safe mode and testing it
out.
close excel
windows start button
run
excel /safe
ok
Then try your ctrl-x combination.
(It sure sounds like a helpful macro to me, too.)
Then next thing you'll have to do is find that macro.
Close excel and reopen it normally.
You'll want to find out if it loads each time excel starts up or if it's
associated with a specific workbook.
So you can try the ctrl-x stuff without loading any workbook to see if it's
already waiting for you.
If it is, then I'd bet that that code is either in an addin (Tools|Addins, one
of those checked items) or in a workbook in your XLStart folder.
You can turn off all the addins, then close excel and remove everything from
your XLStart folder.
Now start adding things back one at a time and restarting excel. When you find
the culprit, you'll have to decide if it's important enough to keep (or if you
can change/fix it).
=====
One more spot to look:
Tools|Options|General Tab:
"at startup, open all files in:" <xl2002 wording>
"Alternate Startup File location" <before xl2002 wording>
Clear out that box. (I've never seen anyone really use this.) And some fill it
in by mistake.
Chip Pearson has some additional notes to help diagnose this kind of problem at:
http://www.cpearson.com/excel/StartupErrors.htm
====
If it's not loaded when you startup excel, then load that workbook where you
noticed the problem. Try it again (just in case something else turned it on).
If it worked, go to the developer and tell them to turn it off!