Office for Mac 2004 Excel Crashes

I have consistently had problems with MS 2004 Excel freezing. I result to using Force Quit and relaunching the application. I've just had a session that froze every other calculation, the worst yet. Virtually at a standstill. Thankfully it was a small document with only a few calculations. Any ideas on how to solve this problem?

I am running the latest version of Snow Leopard, 10.6.8, on mid 2010 iMac.

Thanks

Considered an upgrade to a more recent version of office that may have fixed the issue?