If you are encountering an infuriating problem where Outlook constantly asks you for your password even though you check the "Remember my password" box every single time, then you are in luck because here is how to fix the problem.
Make sure you have logged on to exchange one last time when opening Outlook, and chosen the option "Remember my password"
Make sure Outlook is closed
In any explorer window, paste the following into an address box
The folder will open, simply rename the folder that is contained within this folder (it has a really long file name) – I suggest just adding "-old" on to the end.
Open outlook, and hey-presto, no more dialog box!