Copy. Attempt to paste. Crash.

Version: 2008
Operating System: Mac OS X 10.5 (Leopard)
Processor: Intel

Into week 2 of my mac and Excel 2008, and it's been quiet and calm and
staple.

Today I tried to edit a file that I worked with successfully last night.

Basically, I want to insert a row, copy and paste.
I did the same thing last night without any trouble.

As soon as I try to paste, I get the spinning beachball and have to
force-quit.

Things I've tried:
- saving the file without the macros and using the new file
- saving the file again on the old pc, to xlsx, and loading the xlsx
version to Excel 2008
- working with other files

What I haven't tried (yet):
- opening the file on my daughter's macbook

What's up?
What can I do to try to isolate what's wrong?
Is there an Excel utility that will tell me the health of a file?

Thank you -
concerned but not frantic in Rochester