Troubleshoot formula's between 2003 and 2007
 

Hello,
I have a spreadsheet that is shared on a server. It was created using
Excel 2003. It has some formulas that calculate price for a product.
The 2003 user puts an 'x' in certain cells to selection size, color,
etc.
For 2003 the price is automatically calculated from the combination of
check marked cells.
For the 2007 user, it doesn't do the calculation 'all the time'. I
haven't really figured out a pattern, but sometimes the user will add
an 'x' to a cell that should trigger a price change, then 'enter' or
'tab', but it doesn't always work.
Any ideas!
TIA