Excel shutting down during save

Okay, I've got a strange problem. The macro below WAS (yesterday) working well to save the active workbook to a specific location with a specific name. Now, Excel shuts down when it hits that bit of code. Any idea what would be causing it? BTW, it tries to save to the location; there's an unknown type of fill deposited there, with a name like "7A08C000". If I put an XLS extension on it it says the file format is not valid.

If I change "ActiveWorkbook" to "TwoB" I get the same result. But, if I make a different workbook the active workbook, the macro works.

Sub Save()
Set TwoB = Workbooks("2BDeleted.xls")
        Application.DisplayAlerts = False
        Dim MO As Variant, HO As Variant
        Set MO = TwoB.Sheets("Lookups").Range("H1")
        Set HO = TwoB.Sheets("Lookups").Range("M1")
        Stop
        ActiveWorkbook.SaveAs FileName:= _
            "\\12AUST1001FS01\SHARE10011\Budget\SOBUDGET\CPS\MFR Projections\2011\Current\" & HO & " MFR Projection for " & MO & ".xls", FileFormat:=xlNormal, Password:="", WriteResPassword:="", _
            ReadOnlyRecommended:=False, CreateBackup:=False

        Application.DisplayAlerts = True
End Sub

EDIT: I edited the post to attach a copy of the Lookups sheet.