I have a worksheet that contains numbers, text, blank cells, a text
entry of x, and #N/A entered as =na(), i.e. an error value. I would
like to select (highlight) a range, say A1:D4 and run a macro that
clears the contents of only those cells whose value is x. See sample
worksheet below.

A B C D
1 400 x #N/A text1
2 x text2 200
3 text3 300 x
4 #N/A x text2 500
5
6 text2 20 10
7 - text3 #N/A 500
8 - 300 text1

When I select A1:D4 and run the following macro, it works except for
one detail that I can't figure out. It clears not only the contents
of those cells containing only an x but those cells containing #N/A as
well! I would like the macro to not clear the #N/A cells nor any
other cells unless they contain only an x.

Sub ClearContentsX()
On Error Resume Next
Dim s As String
s = "x"
For Each r In Selection
If r.Value = s Then
r.ClearContents
End If
Next r
End Sub

What am I doing wrong?