I posted this questions several days ago without response, so I've added some
additional information that may help

I'm using Excel 2003.

When opening 2 files and using "windows, arrange" to view side by side, the
left click to minimize, close or go between tabs will quit working. The
issue is
not consistent, and the mouse clicks work fine within the body of the
spreadsheet. This has happened repeatedly, and I can't find a web source to
determine the fix.

I've also noticed that if I drag the border of the "offending" worksheet,
the navigation temporarily works again.

This certainly isn't a life and death issue, but is VERY annoying.

Thanks in advance for your help,

Kim