Certificate Error

Hi there

we have recently moved a few domains over to office 365 in terms of mail hosting only.
after the mail records was adjusted at the registrar we had to run the "internet address" wizard again on the small business server.
after that we kept getting a certificate error when we open our outlook.
the outlook bypasses the small business server for mail right now, but the pc's obviously still speaks to the server as its the local domain controller.
hoe can we rectify this silly popup that keeps coming up when opening outlook?

thanks a lot

Steven
cert.jpg