This refers to a file sharing violation. If you're trying to access a file which is in use by some other process (in your program or is locked by another application) this error may display. Usually a simple restart can fix this issue. Security/sharing permissions also may need to be adjusted. Also, this can be a firewall issue. Try turning the firewall off to test or create a firewall exception for ports 6262, TCP 1723, and UDP 47.