We had an issues recently on a client machine , when reinstalling a CRM 2011 client from x64 to x86.
Once we reinstalled the x86 version we were unable to run the CRM Configuration wizard and if we opened outlook the CRM add-in appeared to be there but was not functional at all.
To fix this we did the following
1, Uninstall the CRM 2011 Client
2,Open Registry Editor
3, Delete the following key “HKEY_CURRENT_USERSoftwareMicrosoftMSCRMClient
4, Re-install CRM Client and it all works