How to find & remove unneeded activex control

I have a spreadsheet with a set of macros. One of the macros used the Microsoft Calendar Control 11 to furnish a popup calendar. However, I have disable this by erasing the page code which referenced the control.

I have given a copy of the spreadsheet to a coworker. Everything worked fine until she got Office 2010, at which point the macros quit working with the error message "Unable to find project or library." Using the VBA References dialog box, I have traced this issue to the fact that the Office 2010 installation on her computer does not have the Calendar Control 11 file. I went into the References dialog & tried to uncheck Microsoft Calendar Control 11, but I get an error message telling me it can't be deleted because it's in use. I've looked through my other macros & can find no references to it. The help box on the error message says to remove the control from the form & then uncheck the box. There are no forms listed in the project window.

Can someone tell me how to find where this may be so I can delete it? While we could just install the control file on her computer, I'd really prefer to clean up the spreadsheet so I don't keep running into this every time I provide a copy to someone.

Any help appreciated.

---GJ Case