Bogus "Out of memory" Warning in VBE?
 

In the "This Workbook" window in VBE, I'm unable to get the object drop-down
box at the top of the window to switch from "(General)" to "This Workbook."
When I click on its handle and select the latter, I get a pop-up box that
says "Out of memory." Clicking OK returns the drop-down to "(General)".
Further, if I try to type anything into the window, I get a warning that this
will reset my project; clicking OK on that crashes the whole thing.

There are only 2 small macros in a couple of modules, each of which
continues to work fine, and in any event I know I have plenty of memory.

I don't know enough about VBA yet to know why this is happening. Is there
something obvious I should do? I'm running Excel 2004 for Mac on OSX, if it's
any help.