Hi,
I have the same experience reported by tomzanca, with the calendar control crashing Excel 2011 (Version 14.2.2)  on a Mac with Lion OS 10.7.4.
I am using the simplest form of the calendar control (dpMode = 0).  Changing the month or year in the DatePick userform works fine, but clicking on a date causes Excel to crash.  In stepping though the code, the crash happens when it gets to EndSub in the TextBox_enter subroutine triggered by clicking on one of the dates e.g.
	Private Sub TextBox20_enter(): Call SetNewDate(TextBox20.Text): End Sub
 
I think it's associated with the DatePick userform being loaded/unloaded.  If in the following code I comment out the Unload Me line, the code exits the TextBox subroutine without a problem, but the date doesn't change to what I selected.
	Private Sub SetNewDate(setDay As String)
    '   Change the selected date
    If canUpdate = 0 Then
        If dpMode = 0 Then
            '           Quits form with selected date for dpMode 0
            Call CalendarModule.returnDate(DateValue(ComboBox1.Text & " " & setDay & ", " & ComboBox2.Text), "no events")
            Unload Me
        ElseIf dpMode = 1 Then
            selectDate = DateValue(ComboBox1.Text & " " & setDay & ", " & ComboBox2.Text)
            Call SetDays(selectDate)
            Label9.Caption = strLabel9C & ComboBox1.Text & " " & setDay & ", " & ComboBox2.Text
        Else
            setDay = Left(setDay, InStr(setDay, Chr(13)) - 1)
            selectDate = DateValue(ComboBox1.Text & " " & setDay & ", " & ComboBox2.Text)
            Call SetDays(selectDate)
            Label9.Caption = strLabel9C & ComboBox1.Text & " " & setDay & ", " & ComboBox2.Text
            Call ListEvents
        End If
    End If
End Sub
 
The Error Reporting log details are as follows:
Microsoft Error Reporting log version: 2.0
Error Signature:
Exception: EXC_BAD_ACCESS
Date/Time: 2012-05-26 06:39:49 +0000
Application Name: Microsoft Excel
Application Bundle ID: com.microsoft.Excel
Application Signature: XCEL
Application Version: 14.2.2.120421
Crashed Module Name: Fm20.dylib
Crashed Module Version: unknown
Crashed Module Offset: 0x0000be89
Blame Module Name: Fm20.dylib
Blame Module Version: unknown
Blame Module Offset: 0x0000be89
Application LCID: 1033
Extra app info: Reg=en Loc=0x0409
Crashed thread: 0
I suspect this is a bug in Excel 2011 for Mac.  Any assistance to workaround it would be welcome.  I need a portable calendar control to work on Excel 3003 / 2007 / 2010 for WIN and 2011 for Mac, and this would be ideal - if I can get it to work.