Here are three code fragments. The first one works propely, the second two
cause Excel to crash. Can someone tell me what I am doing wrong? Thanks

The following code works properly:
Dim VBCodeMod As CodeModule
Dim LineNum As Long
Set VBCodeMod =
Workbooks(wb).VBProject.VBComponents("ThisWorkbook ").CodeModule
With VBCodeMod
LineNum = .CountOfLines + 1
.InsertLines LineNum, _
"Sub Workbook_Open()" & Chr(13) & _
"setLookupList" & Chr(13) & _
"End Sub"
End With

This code causes excel to crash:
Dim VBCodeMod As CodeModule
Dim LineNum As Long
Set VBCodeMod =
Workbooks(wb).VBProject.VBComponents("Sheet1").Cod eModule
With VBCodeMod
LineNum = .CountOfLines + 1
.InsertLines LineNum, _
"'Private Sub Worksheet_Change(ByVal Target As Range)" & Chr(13) & _
"'doIt Target" & Chr(13) & _
"End Sub"
End With

Similarly, this code also causes excel to crash:
Dim StartLine As Long
With Workbooks(wb).VBProject.VBComponents("Sheet1").Cod eModule
StartLine = .CreateEventProc("Change", "Worksheet") + 1
.InsertLines StartLine, _
"dotIt Target"
End With