I've seen this kind of behavior after software was added to a 3rd party
application (specifically the Deltek Premier accounting system software) to
provide output directly to an Excel file.
I was unable to determine what caused the problem and ended up doing repair
installations of Excel on the involved systems to correct it.

Give the setting change that Dave Peterson and RagDyeR recommended before
going that route. That's one thing I did NOT try while investigating the
problem on the systems I spoke of.

"wludwick" wrote:

Excel files will not open from windows explorer, only the excel software
starts; must start excel first, then look for file before it will open; IT
people have re-installed windows twice and downloaded all recent updates.