I have had no problems with my blog until this week, and now it is suddenly down. I can't access the back end, either (which is why I can't be completely sure which version of WordPress I'm running -- it would have been whatever was most current in August of 2011). I have not added any new plug-ins in several months; the theme is TwentyEleven. ReadyHosting is trying to diagnose at their end, but they've just had to upgrade the ticket after their initial attempts failed. They suggested I try the support forum here.