Excel 2003 on WinXP.

I have a workbook that I have distributed to other users; the key elements
(I think) are that there are several worksheets, and when macros are enabled
the default sheet is hidden and a data entry sheet is shown. The data entry
sheet has a commandbutton on it that runs a macro to bring up a userform for
data entry. The sheet itself shows the data, but is protected to prevent
direct data entry.

On one PC, there are two extra toolbars showing in Excel. When this file is
opened on that PC (macros enabled) the data sheet is shown, but the button
ususally never appears, or when it does, clicking once on the sheet itself
makes it disappear.

I've looked in the VBE and there are no other projects at all (no adobe,
nothing but my project), and I looked in the XL start directory and didn't
see anything there either, and there are no add-ins checked (not even the
analysis toolpack).

I'm stuck, because I can't figure out where else these toolbars might be
coming from so I can remove them to see if they are really the cause of the
commandbutton disappearing. I can uncheck them in the view/toolbars menu,
but when closing and re-opening Excel, one of them always reappears, so
something is setting it to be visible every time Excel is opened.

Where else should I be looking?

Thanks,
Keith