Runtime Error 7, Out of Memory
 

I'm building a rather extensive UserForm in Excel 2003, SP-1, on Win
XP, SP-2. As I've been adding more stuff to it, I've reached a point
where, when I open the document file (double-click on the .xls file),
there is immediately presented an error MsgBox "Run Time Error 7, Out
of Memory." If I then press the default response "End" button, I get
the "Security Warning asking whether to enable or disable macros, and
everything seems fine from there on, as if the initial error message
were spurious.

I'm continuing to work, but what are the limits on how "fancy" a
userform and its code can become before Excel chokes? Am I on thin
ice? Some likely cause that I can "fix" or work around?

Thanks,

Fred Holmes