If you've noticed in the last few days that your Asset Intelligence in ConfigMgr has stopped working, with the error "Connection failed -bad certificate" in the console, it's in all likeliness because the certificate has expired.
You could also check Aiupdatesvc.log for the following messages:
Asset Intelligence Catalog Sync Service Warning: 0 :<Log Date>:WebException trying to enroll: Status = ProtocolError
Asset Intelligence Catalog Sync Service Error: 0 :<Log Date>:Exception attempting sync - The request failed with HTTP status 403: Forbidden.
The default certificate in SP1 and SP2 had an expiration date of 25th April 2011.
It's now the 18th May and MS just released yesterday a hotfix to replace the certificate and get you back up and running.
If you're on SP2 then visit this link to grab the hotfix:
If you're on SP1, either follow the instructions here or get on with upgrading to SP2 ;)