Hello all. Just to add my two ha'p'th:
Win7 64Bit (Er... I notice that the time is shown here an hour out - advanced - 'though we're in GMT in UK)
Pop-up told me about half an hour ago that my Virus Definitions were out of date.
Bit strange; on Auto and Streaming.
Opened interface, clicked on update, received message as per OP
THEN noticed that it was the PROGRAM that was registered as out of date, (Which I have set to Notify Me).
Rebooted. Ran Update. Same result.
This is merely Public Opinion, you understand. : )