We had one that was brand new, and yet we had to keep going out on for the same thing: the phones would ring once, then go to auto attendant. It was supposed to ring four times, then go to auto attendant. I think Comdial even replaced the system once, because they couldn't find a reason why it kept happening.

After 4 or 5 times of the same problem (all of which were cleared up by cold starting), we took a chance and replaced the UPS. The problem never returned. It turns out the UPS was a Tripplite 600, and we had been having problems here and there with them. Needless to say, after going thru different problems with at least a dozen of these UPS's, and having to pay to ship them back to Tripplite, we changed brands.

Bottom line on the DX80, though, is that the previous posts are right on the money! A cold start will almost always cure the strange problems. A firmware update is my other solution for those problems that can't be explained (have you ever read a bug report on things reported and fixed???)