Microsoft Outlook 2010 email stuck at outbox, the mail will successful send out after you restart the outlook

Dear Mdm/Sir,

I've a problem on Microsoft outlook 2010 with service pack 2.

Sometime it cannot send out email, the email will stuck at outbox.  It only work after you restart the outlook and resend.

I've add the 2 email account into this Outlook profiles and running at Windows 7 professional Operating system.

I've try run the Outlook into safe mode, but it can't solve the problem too.

I also create a new email profile and user profile, but still cannot solve the problem.

Please help,

Thank you,

Wcnw