Outlook Error: This application has failed to start because MSVCR80.dll was not found.

This error often caused by add-ins installed by Norton security products, but if you have an Acer computer, the eDataSecurity add-in for Outlook may be the cause. Note that these two applications are the most well-known cause but other applications may cause it as well. 

Unloading the offending add-in will usually fix it, if not you'll need to uninstall the application.

In Outlook 2003, go to Tools, Options, Other tab, Add-ins, location the offending add-in and disable it. In Outlook 2007, you'll go to Tools, Trust Center, Add-ins. If its not listed, you'll need to edit the registry.

1. Open the registry editor (Start menu, Run, type regedit)
2. Browse to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins
3. Locate the suspected add-in in the list
4. Set the LoadBehavior to 0

More Information