The Classic outlook plugin would not not install on Windows 7 using IE10 with Outlook 2010. The CRM tab was not visible in outlook after installation.
The user on the machine had no admin rights.
When installing the Classic Outlook plugin, the user installing it must have admin rights on the machine in question.
The solution would be to give the user standard user admin rights and install the plugin. Once installed, take away the admin rights for this user.