I have a large and complicated excel file with a lot of named cell ranges.
Every time the user makes a change, a macro updates every named range,
changing data validation as necessary, changing fonts to signal errors, and
in some cases entering new excel formulas. As long as I work on this file
stand-alone, everything works.

The problem is when I open another file with cell formulas that refer to
this file. As long as that second file is open, the macro in my origonal
file crashes. It seems to crash at the point where it changes any cell
formula. I'm not certain, because it doesn't go into debug mode, but rather
simply stops. When I try to trap the error, I read it as error 1004 -
"Application Defined or Object Defined Error"

I have not found any way to make this problem go away, other than closing
the file that links to this one. Anyone know what is happening here?