If you get a message that says "Windows computer is not accessible..." and you are on a domain network here is the fix that generally works:
- Go to your DNS on your domain controller
- Look for the FQDN computer you are trying to access in the list. It will MOST LIKELY be the wrong IP assigned to it.
- Delete that DNS entry.
- Go back to the computer trying to access that one and do a "ipconfig /flushdns" and the issue will be resolved.
Bottom line: The client trying to access that shared computer has the wrong IP, and is cached in the domain DNS, by removing the entry and flushing it now has the correct FQDN IP.