I've searched around trying to figure out how to solve this issue, but the problem is I don't know what exactly to call it. I've tried everything I can think of to fix and I'm still stuck - Short of retyping all the data, which I did for a few small sheets.

Using 2007. Formulas only work when I click on the cell and hit enter again. If its a simple sum function and I add 10 to one of the cells, it doesn't add automatically. Same thing for -,/,* and more complex formulas. This only happens in old files/sheets that are in Compatibility Mode (read background below).

Background:
I had 2003 and had a buddy backup all the files from my PC (excel, pics, docs, etc) on an offline server I keep offsite. In the process he loaded office 2010 on my PC, but it turns out it wasn't a copy I could use long term as I needed to be connected to his corporate network for the registration to finalize. Once I discovered the 2010 issue, I couldn't go to him because he's now over in Afghanistan serving, so I loaded 2007 (i have a dozen or so licenses of 2007 unused).

I'm not sure if its an issue with 2003 converted to 2007, or if its the 2010 converted back to 2007, or 2003 converted to 2010 converted to 2007.

Thank you in advance for your help.