A Huge Thanks for this tip Stephen.

I was working on an important worksheet, had a Skype call to make, and updated my skype application which was seriously out of date (well, why not?). Went back to finishing off the spreadsheet later in the day and the behaviour was truly bizarre. I messed up quite a few cells before I realized something was SERIOUSLY wrong. Spent two hours trying to make Excel behave. How can a person associate Excel problems with some totally non related application. I have worked in the IT industry for 30 years and have seen my share of crazy bugs but this one deserves a prize. The fact that Skype is a Microsoft company makes allowing such a fault in this software raise real questions about Microsoft quality control proceedures.
Anyhow for anyone seeing this bug let me clarify the fix:
1) go to Control Panel
2) Select show/delete softward choice
3) You will see two Skype applications
4) Delete the one saying Skype click to call

Problem fixed
Howie