Yes there is an explanation. The proxy server kept locking up ruining access to mirrorlist.clearos.com. I kept having to reboot it. It is all I can do as I don't otherwise look after it. Also, it tended to lock up in the early morning US time and, as I am in the UK I was already up and could restart it. Since then, the issue has been fixed, but there are better fixes on the way. They have been partly implemented and anyone with the latest yum-marketplace-plugin could switch to it by updating their hosts file. Unfortunately if I update the A records, it would lock out anyone who had not updated, and anyone installing from any of the iso's. We are working on removing this restriction so I can update the A record.

I don't think I've had to reboot it nor for a month or so, so the initial fix seems to be good. The fix we are waiting on will be better....