Mark,
I am not sure about the Microsoft article - looks a bit complicated to me.
This is what worked when we had a similar problem.
Tools, options, general make sure the 'ignore other applications' is not
selected.
If this does not sort out the problem you may need to go to this as in this
post from Beth Melton which we found when we had the same problem and it
solved it.
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It sounds like is a problem with the file associations. Go to Start/Run and
run this command:
Excel /regserver
Note that there is a space before the forward slash.
If you receive an error, you may need to browse to Excel.exe and include the
full path. It would look something like:
"C:\Program Files\Microsoft Office\Office\excel.exe" /regserver
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Beth Melton
Microsoft Office MVP
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Hope this helps,
Barbara