Encountering the same problem with one of our laptops. Runnning Office 2007 on Windows 7.
Here is an intriguing fix which seems to have helped others:
After viewing the Outbox, messages won't send
As you see, the author suggests uninstalling or deactivating Outlook Add-Ins.
That is what I am trying, but I have run into a problem: On some add-ins I get the following message:
"This Add-In is installed for all users on this computer, and can only be disabled by an administrator." But the owner of the laptop (basically a one-person laptop) *is* an administrator. Does anyone know how to solve that problem?
The addins thatI cannot disable are:
Business Contact Mgr for Outlook (cited by the author above as a potential problem)
Evernote Outlook Clipper
iCloud Outlook
MS Outlook Mobile Service
Outlook Change Notifier
Windows Search Email Indexer
MS VBA for Outlook.
Anyhow, hope the above helps. Maybe we can put our headsd together and get it solved. Seems to be an issue which is hitting a numeber of people. Maybe virus going around? Ran Norton but it just picked up some tracking cookies.