I have the following that has worked for months and now has stopped? Is
there some limit? It basically takes a number (Fixed digits like 1234 + a
calculated part) and pastes it into a cell.

Sheets("Serial Number Log").Select
Range("A1").End(xlDown).Offset(1, 0).Select
Sheets("DO NOT DELETE").Select
Range("G54").Select
Selection.Copy
Sheets("Serial Number Log").Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
:=False, Transpose:=False
ActiveCell.Offset(0, 23).Copy
ActiveWindow.ScrollWorkbookTabs Position:=xlFirst
Sheets("Work Order Form").Select
Range("H25").Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone,
SkipBlanks _
:=False, Transpose:=False