Mail App Help

I have a bit of a strange problem,

Since doing the latest OSX update last week, every time i close the mail app all my accounts get deleted apart from my mobile me account.

I have a google mail account and a hotmail account and i have to keep adding them as new accounts. The strange thing is that once i add them the messages are all instantly there (i mean not being downloaded from the server).

Has anyone had this issue before? Sorry if it has been posted before, however it is very time consuming having to add a new account every time i open mail!!

Thank you for the help!