If the installation of the Outlook Plugin has not been successful it is a very good idea to manually uninstall it before trying to re-install it.
Please see below the instructions for manually removing the Outlook Plugin.
Check User Access Control is set to the minimum level and reboot PC if this needs to be changed.
Uninstall Sage crm client applications from control panel (if it exists - don't worry if it does not)
Unregister the 3 outlook plugin files by entering the below into a command prompt
regsvr32 /u "C:\Program Files (x86)\Sage\CRM Client\Outlook Plugin\crmoutlookplugin.ocx"
regsvr32 /u "C:\Program Files (x86)\Sage\CRM Client\Outlook Plugin\crmoutlookplugin1.dll"
regsvr32 /u "C:\Program Files (x86)\Sage\CRM Client\Outlook Plugin\crmoutlookplugin2.dll"
Delete the CRM Client folder from C:\Program Files (x86)\Sage\
Delete the Accpac folder from -
Windows 7 - C:\Users\”login name”\app data\roaming\ACCPAC
Open the registry (by running regedit) and delete these keys if they exist:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Sage\Sage CRM\Outlook Plugin
Log into CRM via Internet Explorer 11 and install the plugin again