Excel Macro suddenly starts giving incorrect ActiveCell Data

[Paul_Hossler]

Not sure, but it seems that you're always making ActiveCell column A in whatever the activeRow is

    activeRow = ActiveCell.Row
    Cells(activeRow, 1).Select    
    If ActiveCell.Column <> 1 Then

I'm guessing you wanted something like this

Option Explicit

Sub CellPost()
    Dim r As Range
    Dim val As String
    Dim activeRow As Long    
    Sheets("Gunsmoke").Select    
    If ActiveCell.Column <> 1 Then
        MsgBox " Select a Lot Number from Column A "
        Exit Sub
    End If    
    If ActiveCell.Interior.Color = vbYellow Then
        MsgBox " This Lot was already Invoiced"
        Exit Sub
    End If    
    Set r = ActiveCell            
    Sheets("Parts&Labor").Unprotect
    Sheets("Parts&Labor").Range("A18:E22").Locked = False
    Sheets("Parts&Labor").Range("E3").Value = Now()
    ' MORE POSTING IS DONE HERE                      
    r.Interior.Color = vbYellow
    r.Offset(0, 8).Value = Now()
   ' MORE POSTING IS DONE HERE
End Sub