I'm on cossacks and have been since May of last year to develop my site.
I don't get 90% downtime, but it has got progressively worse recently (strangely it seems since the last "update") to the point where I get about 25% downtime at peak times.
Fortunately, because I'm from UK, our peak times are before the main US ones!
I would like to raise a very valid point here.
I moved from zymichost last year becuase their servers were far worse than these and I appreciate the fact that a host would offer free space + php + MySQL Server - which is unusual.
However, as I am a serious site developer, my site is now almost at the point where I will migrate to a paid host.... but due to the reliability of the Cossacks server and the fact that it's mail blacklisted with a lot of mail servers, I'm not tempted to get paid hosting with X10!
Come on X10.. if you're going to offer a free service, please lets have a service that's at least reasonably reliable!!!