They were just temporary, as the CPU load was very high earlier. I saw these values for instance
09:00:49 up 18 days, 14:34, 3 users, load average: 23.93, 26.61, 23.4
I've been using site monitor on my account since 19th February, this morning it was still at 100% (yay!!) but that has since dropped to 93.07% due to the 500 errors (and at one stage the server not responding at all)
Still... good work guys! The service is really good save the occasional hiccup on the server.