I've had nasty problems with the collation settings. The strange thing is I had never explicitly done anything to mess about with collation settings, it seemed to happen spontaneously. I work in Italy, some kind of mess up between English and Italian versions of SQL and/or Windows.

I did find a script (I think on this site, don't ask me where) for easily changing collation settings on all tables in a DB, if anyone is interested I can send it.