rules get unchecked

My Apple mail rules get inactivated regularly by themselves, I do not understand
yet what makes this happen. Just when I occasionally open the Apple Mail
preferences, I see some of the SpamSieve rules are unchecked. Does anybody
have similar experience?

I don’t know what would cause that. Are you using .Mac syncing?

I do not use .Mac syncing, but I may have tried to sync with an imap server
that is down now. It may have been that the rules were trying to move stuff
into folders that were on the server that was down, and thus failed: I will have
to watch whether it happens even under normal conditions.