FollowHyperLink Issue

[lillicob]

I am using the following code to unhide a worksheet and navigate to it when I click a hyperlink. For some reason, this code will fail to execute for periods of time when I open my workbook, but not every time I open it. Sometimes it will start working again in 20 minutes (without me reopening the workbook or saving it) sometimes it will work again in a few days. Any ideas on why this code will stop working and start working again without anything being changed?

Private Sub Worksheet_FollowHyperlink(ByVal Target As Hyperlink)
    LinkTo = Target.SubAddress
    WhereBang = InStr(1, LinkTo, "!")
    If WhereBang > 0 Then
        MySheet = Left(LinkTo, WhereBang - 1)
        MySheet = Replace(MySheet, "'", "")
        Worksheets(MySheet).Visible = True
        Worksheets(MySheet).Select
        MyAddr = Mid(LinkTo, WhereBang + 1)
        Worksheets(MySheet).Range(MyAddr).Select
    End If
End Sub