I frequently get the message below when trying to open an email in Outlook 2010. Usually it occurs when I leave Outlook (but do not close it) and work on something else then return to Outlook.
The message is:
Cannot open your default e-mail folders. The file C:\users\Dottie\AppData\local\Microsoft\Outlook\Ou tlook.pst is in use and canot be accessed. Close any application that is using this file, and then try again. You might need to restart your computer"
Sometimes I can close Outlook, go to the Start menu and re-open it from there and everything works, but most of the time I do have to restart my computer.