Outlook experienced a serious error: 'microsoft vba for outlook addin'

Hi,

I wonder if anyone can help me with this problem I have been getting.

I wrote a macro in Outlook that strips unwanted text from the Subject line, here it is:

Sub CleanDC()
Dim OutlookApp As Outlook.Application
Dim myNamespace As Outlook.NameSpace
Dim myItems As Outlook.Items
Dim myItem As Outlook.MailItem
Dim dcFolder As Outlook.MAPIFolder
Dim s As String

Set OutlookApp = CreateObject("Outlook.Application")
Set myNamespace = OutlookApp.GetNamespace("MAPI")
Set dcFolder = myNamespace.GetDefaultFolder(olFolderInbox).Folders("Lists").Folders("DC")

Set myItems = dcFolder.Items.Restrict("Not ([Categories] = 'Cleaned')")


For Each myItem In myItems
If (myItem.Class = olMail) Then
s = myItem.Subject
If (InStr(1, s, "[DC]", vbTextCompare) > 0) Then
s = Replace(s, "[DC]", "", 1, -1, vbTextCompare)
s = Replace(s, "re:", "", 1, -1, vbTextCompare)
s = Replace(s, "fwd:", "", 1, -1, vbTextCompare)
s = Replace(s, "[]", "", 1, -1, vbTextCompare)
s = Replace(s, " ", " ", 1, -1, vbTextCompare)
s = Trim(s)
myItem.Subject = s
myItem.Categories = "Cleaned"
myItem.Save
End If
End If
Next
MsgBox "Done"
End Sub

The macro seems to work fine, except that when I close Outlook and then open it again I get the following error:

Outlook experienced a serious error the last time the add-in 'microsoft vba for outlook addin' was opened. Would you like to disable this add-in
To reactivate this add-in, click About Microsoft Office Outlook on the Help menu, and then click Disabled Items

I have created a self-signed certificate and I have added it to my certificate store, I then signed the project with the certificate.

What am I missing

Any help would be greatly appreciated.

Thanks,

Andre