A mis-configured SQL Server filled up the servers discs today, which have caused in-stability and downtime on umbraco.org and the forum.
It was not umbraco related, but simply me who thought I was a DBA 18 months ago and made wrong maintanence plans - shame on me. I'll have a proper DBA looking over the setup as soon as possible, so it hopefully won't happen again.
Sorry for the inconvenience!