I used the following two methods to determine the existence of a spreadsheet
on one system, but using the same statements on another system I get Error
9, subscript out of Range. Both systems are running Windows XP and Office
2003.
The worksheet does not exist at the time either of these statements are
executed.

If Len(Worksheets("XYZ").Name) 0 then do this or that

Worksheets("XYZ").Activate
If Err.Number < 0 then do this or that

Why do these work on one system and not the other? Is it possible that
there is a setting that needs to be change within Excel to make this work?
Very perplexing. Any assistance would be greatly appreciated. Thank you in
advance.