I have a user who has Office 2010 Pro and Windows 7 Enterprise installed. We are using Exchange with Office 365 accounts.

The problem is once or twice every 3 to 5 days when he opens a new email, reply's to one, or forwards one, the email window stays open and won't send after clicking the "Send" button.

1. All Windows and Office updates have been installed.
2. I have deleted the existing .OST file.
3. I have created a new Outlook profile.
4. I have un installed Office 2010 - Deleted all old leftover files and registry entries that were left and re installed Office.

Nothing has fixed the problem. It can be days in between this issue from happening and the only way to get around it is to re create the email in a new window, close the corrupted one and the new one will send out fine. Outlook is not locking up at all when this happens. The Send button on the email window just does not work?

Also want to add this is happening to random email address they send out to so it's not just one that we are seeing happen to. I can't force it to happen either.

Hi, please troubleshoot this from running Outlook in Safe Mode, to determine if it is 3rd-party add-ins related.

Press Win + R and type outlook.exe /safe in the blank box, then press Enter.

If theres no problem in Safe Mode, disable the suspicious add-ins to verify which add-ins caused this issue.

We also suggest you perform a clean boot to troubleshoot this issue:

http://support.microsoft.com/kb/929135#appliesto

If your case is a message stuck in outbox issue, please try the following steps and let me konw the results:

1. Work offline, move the stuck mail into another folder. Restart Outlook and Work online to send it again.
2. Temporarily uninstall or disable firewall and antivirus software.
3. Test in Outlook safe mode.
4. Create a new profile and re-setup your account.

Regards.

Melon Chen
TechNet Community Support