Exit worksheet selection if more than 1 cell selected

Hi,
I have a slight problem with a Worksheet_SelectionCharge event. I would like to exit the sub if more than one cell is selected. I am using use:

If Target.Cells.Count > 1 then Exit Sub.

It works fine for a relatively small number of cells being selected but if I select the entire sheet I receive a Runtime Error # 6: Overflow situation before it will exit the sub. I have tried stepping over this with Resume Next and GOTO 0 catches. Any ideas on how this can be worded to prevent the overflow?

Thanks in advance,

Chris