From mhdir to mbox.

Something strange happened today, I woke up to find that mutt - my mail client - has forgotten all the new labeled and flagged messages. This happened to me about 2 times in the last year or so. It's very annoying especially when you have +2000 email in your inbox folder.
I'm almost sure that it's not mutt fault.
I tried to mark some emails as new, but the marke are gone whenever any new email arrives, Now this is really new!
I'm almost sure it's rcvstore fault. But how do u debug/fix something like that!
I'm using mhdir mailboxes, I wanted to convert them to mbox format as mutt takes long to open a mailbox, And takes long time to scan the mailbox for changes, But I was lazy to do it.
Thanks google, I found a nice script, mh2mbox from here.
Though I had to convert them one by one, But It wasn't a hard process. And after all, I had a Chance to clean some unused mailboxes ;-)
Anyway, After modifying me ~/.procmailrc, Everything is smooth now.