ActiveWorkbook.SaveAs Opens a File

I have a user who is having a weird problem with this macro:

Sub SAVEFRESH()
 Calculate
 ActiveWorkbook.SaveAs Filename:="NEWFILE.XLSM", FileFormat:=xlOpenXMLWorkbookMacroEnabled, _
        Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
        False, CreateBackup:=False
End Sub

The macro is in a mostly blank spreadsheet with a few cells that are updated from other worksheets with the Calculate command.

The macro is activated through a custom button on the ribbon. On only one workstation, when the button is clicked, the current copy of NEWFILE.XLSM opens in the background. It works on all other workstations.  All workstations have the same configuration: Windows 7, Excel 2010. I am at a loss as to where to start with troubleshooting. Any help would be appreciated.

Thanks.

-R