Update Outlook and/or the Microsoft Office suite to the latest version to resolve the issue.
As a workaround you can disable the AntiVirus Outlook plug-in. The location will vary depending on which Office suite you are using.
Examples
In Office XP:
- In Outlook click Tools > Options.
- Click Other tab.
- Under General section click Advanced Options.
- Click Add-In Manager.
- Uncheck Symantec Antivirus Outlook Protection.
- Click OK.
- Click OK.
- Click OK.
In Office 2007:
- In Outlook click Tools > Trust Center...
- Click Add-ins
- Choose Exchange Client Extensions from the Manage: drop down menu and click Go...
- Uncheck Symantec AntiVirus Outlook Protection.
- Click OK.