Just an FYI for others that may run into this problem. I found several others had posted the problem to various forums. I tried the various proposed fixes and none worked for my particular case.

Anyway, my macro creates a custom sort list, sorts a range, then deletes the custom list. Excel 2010 would crash upon attempting to save the file after running the macro. I finally narrowed the cause to this line of code:

Application.DeleteCustomList Application.CustomListCount
The best method I could come up with to prevent the crashing was to add the following lines:

'Just for application crash prevention...
'(initiating a save after deleting custom sort list)
ActiveWorkbook.Worksheets("<sheet name>").Range("A1:A2").Sort Key1:=Range("A1"), _
 Order1:=xlAscending, Header:=xlNo, _
 OrderCustom:=1, MatchCase:=False
...where A1:A2 is an empty range.

I'm open to a better method to prevent the crashing, but short of a better method, the above worked for me.