Using a range in Sum Function

I have run across an oddity in Exel 2010 Trial Edition.

If I define a range to be cells c1, d1, f1 and g1 using the Name Manager and
then put the following in another cell:

=Sum(range name), the function returns the proper value.

BUT, each time I open the worksheet after just viewing it (not changing
anything), Excel asks me if I want to save the changes. I didn't make any
changes so why should it ask me that?

Is there a solution to this?

Thank you.