The first thing I'd try is to reregister excel:

Close Excel and
Windows Start Button|Run
excel /unregserver
then
Windows Start Button|Run
excel /regserver

The /unregserver & /regserver stuff resets the windows registry to excel's
factory defaults.

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If that doesn't help, are you sure that's the exact error message you get?

AndyCowboy wrote:

I now can not open any excel file from my desktop shortcuts. This occurred
after I updated to the latest Microsoft update. I get the following; .xls is
not a valid Win32 application." This just occurred after updated to XP
service pack 2.

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Dave Peterson