This sometimes happens even when I am using the wiki infrequently. For instance, I just tried to get the FAQ page (http://ourproject.org/moin/Ourproject_FAQ) after not having accessed the wiki for I think about ten minutes, and I got the error message. Of course this is annoying and slows things down a lot. My hunch is that this is not related to my own use but happens when other users are using the wiki heavily. Maybe you were not aware of this problem; just letting you know.