Microsoft Outlook 2007 Refuses to Remember Emai Password

For some reason Microsoft Outlook 2007 has stopped remember the password for my primary email account – I have three accounts that it accesses. Although the password is typed into the account profile, and remember password is clicked, each time it checks the mail, it asks me to re-enter the password. Well, that is not precisely true, it will remember the password for a couple of minutes, but after about 5 minutes, forgets it. This is really annoying, what can I do?

Kevin