633 error means the port is already opened!
It means ur connection was not terminated but went in Dormancy mode, i.e., there was no data transfer but the connection was active!
Thats why when u tried to reconnect, it gave error!
U can do one thing!
When u connect, try to PING the Server IP address, which u can see thru the net icon in system tray!
And if u again get that 633 error, then simply remove the cable from phone and then attach it again!