7310 main phone with two other extensions. Norstar Meridian with Flash. For some reason my "general delivery mailbox" says it's full if someone tries to leave a message. When viewing from the handset it show there are no messages but no one is able to leave messages. I've tried a couple times to delete and reinstate the mailbox with no avail. There are two other extensions on this phone system that function just fine for years now. Any assistance is greatly appreciated!