I have the following code that is intended to prevent the user from entering
certain characters. It works fine if the user goes cell by cell and enters
values. The problem occurs when the user copies values into a range of
cells. Is there a way to work around this?

Code:

Private Sub Worksheet_Change(ByVal Target As Range)
Dim blnIsOk As Boolean

blnIsOk = True
If Target.Column = 7 Then
If InStr(1, Target.Value, """") Then
blnIsOk = False
ElseIf InStr(1, Target.Value, ",") Then
blnIsOk = False
ElseIf InStr(1, Target.Value, "&") Then
blnIsOk = False
End If
End If

If Not blnIsOk Then
MsgBox "Commas, double quotes, and ampersands (the & symbol) are not
allowed in product descriptions. Please refer to the Product Description
Policy. Thank You."
Application.Undo
End If

End Sub