If your rig has bad internet connection, this can happen. I have very strict timing rules to prevent spending too much time waiting for single mining rig. If connection is not established in 2 seconds, rig is reported as OFF, if data is not sent in 2 seconds, rig is reported as OFF.
Hmm, I see... My internet connection is definitely OK, I got cable and it's usually very stable. Also CGminer didn't report anything(bad connection, etc...) when I saw the "OFF" on the website. These 2 seconds will not pose a problem when your service becomes more popular? What about DDOS attacks?