when i expand one of my mail folders the program closes

recently when i go to expand one of my main mail folders the client closes when i click on the expand arrow. other folders expand fine. it also sees all of these folders when i added a test folder to the directory so they are there. any way to recover from this other than restoring from an old backup?

The database check and repair after next restart should restore it. Did it succeed?
If it happens on regular base please send me an email to [email protected] .