Excel Constantly Recalculating When ANY Change is Made

Can someone suggest some tips on how to track down (and hopefully fix) an Excel file that recalculates (taking several seconds each time) whenever ANY change is made?
I have a ~2 MB .XLSM file that is fairly complex (about 20 worksheets) and includes a number of macros. But the changes I make (such as formatting a cell) are not triggering any macros, and there are NO volatile functions (that I can find) used anywhere in the file.
Strangely, if I also open any other file (even a simple 10 KB file) and make any change to THAT file, Excel still recalculates the 2 MB file each time I change the OTHER file!
I'm running Excel 2007.

Is there anything else (besides volatile functions) that might be causing this?

Yes, that's what I've been doing.
But I'd still like to fix the constant recalculation if possible.

Originally Posted by bebo021999

Is there any Worksheet_Change event?
Is there any Worksheet_Selection event?

Not on the sheets that I am making changes on. And for my example of opening a second small file, that file has no macros at all (but the main file still recalculates whenever I change that second file).

Sounds like you either have volatile functions, or you have exceeded the limit of the calculation map which (I think) means the whole workbook becomes volatile.