In the troubleshooting steps you listed, it looks like you may be modifying the CRM database changing the isDisabled column. Care should be used when making changes to ensure you remain in a supported configuration
Have the user go to another machine that is working, and log into CRM through IE to see if he continues to see this error. You can also have a working user do the same on this machine. This will help isolate the issue to the CRM user or to the
machine.
If it is the machine, you should look at
1. What browser version he is running?
2. Make sure the clock on his machine matches the CRM server time (make sure to check the time zone is correct as well). You may even want to make sure the bios time is correct.
3. Uninstall the Outlook client and Windows Live ID Sign In Assistant. Concentrate on being able to get the user signed into CRM through IE first before focusing on his Outlook client. Once that works, reinstall the Outlook client.
4. Try installing fiddler and monitor the packets as IE attempts to connect to CRM. If it suddenly works while fiddler is installed, then there is a proxy issue at play because fiddler sets up its own proxy. But fiddler will show you if there
are any redirections happening.
5. Check to make sure the workstation is not using any host files to point to CRM. Maybe do a nslookup to the CRM server. Make sure that the machine is still joined to the domain and logged in.
6. Are there any group policies the user or machine is in?
7. Check the firewall on the workstation to make sure something like a new antivirus install didn't block something.
Jason Peterson