Workbook Open but not visible (and not HIDDEN?!?)
 

I have a workbook that when I open it up, it is not visible. It sometimes
shows up in the "switch windows" button as the selected window (no other
sheets open, fresh Excel session). It is also not a selection in the
"Unhide" option. Yet it is still not visible.

When I go to "arrange all" or "create a new sheet", the originally opened
workbook appears.

Other times, the workbook fails to open.

When it does become open and visible, it gives me the error "A formula in
this worksheet contains one or more invalid references. Verify that you
formulas contain a valid path, workbook, range name, and cell reference."

I initially suspected links (there are none) and then chart references
(these also seem fine). The workbook is less than 1MB. It is being viewed
in compatibility mode in 2007 (it's a 2003 book, but we have to publish it to
users with 2003 and 2007).

Any thoughts appreciated!