I would like to allow users to clear the contents from all of the unprotected
cells in multiple sheets of a workbook, simultaneously.

I read a similar posting on the subject in
microsoft.public.excel.worksheet.functions, posted by sstea, titled How to
clear multiple cells of input data in Excel simultaneously. The suggested
code was as follows:

Sub ClearForm()
Dim c As Range
For Each c In Sheets("sheet1").UsedRange
If c.Locked = False Then
c.ClearContents
End If
Next

End Sub

This was a good start but I ran into errors.

1. Runtime error '1004'. Cannot change part of a merged cell. How do I
edit this code to clear the contents of unprotected merged cells?
2. How do I make this simultaneously work on multiple sheets in the workbook?