I recently had Office 2007 on my work PC. Others are still on 2003. All
spreadsheets created so far are on 2003 and I recently changed one of them to
include look up functions from lists and, it has dates and formulas to
calculate network days etc.

Opening this in 2007 causes 2007 to crash continually and recover the file -
all formatting is lost.

Any ideas on how to solve this?

Also - every time I open excel in 2007 it says it's in compatible mode -
what does that mean exactly?

Thanks!