Earlier today some of our On Demand customers experienced a series of errors after logging into their FogBugz On Demand account.
While the root cause is still unknown (the web server wasn't showing us any reason why it was malfunctioning), we do recognize that we can catch this error before it becomes wide spread. We will expand our monitoring system this week to dig further into On Demand and look for errors when performing standard operations (opening a case, looking at filters, etc).