Symantec Clients Showing as Offline/Outdated on Manager

My Symantec console is showing at least 50% of my clients as offline or with out of date definitions. The clients themselves are receiving their updates with no issues, they all seem to be up to date. The problem only seems to be with the reporting of the clients back to the server. I can ping and telnet between clients and server. The clients are a mix of Win XP and Win 7.

Any help would be appreciated.

Thank you!