Loop Through Worksheet Delete Row Until Specific Value

I'm trying to loop thru the worksheets(which are imported from a web form in Outlook) and delete row 31 until the text "PARTS" is reached.
I need to do this to format each sheet exactly for export to an Access database. The code below works when I step thru it but when I save and run from a button it gets stuck in an endless loop. Any help would be greatly appreciated.
JB

Sub DeleteRow31()
Dim w As Worksheet
Dim rng As Range
For Each w In Worksheets
w.Select

Do Until Cells(31, "B") = "PARTS:"
Range("B31").Select
Range("B31:K31").UnMerge
Range("B31").Select
If Not Cells(31, "B") = "PARTS:" Then
Selection.EntireRow.Delete
End If
Loop
Next w
End Sub