Check out the cd-key grabber from ShadowFrench.
http://www.securegamers.com/shadowfr...keygrabber.php
Start it, start
WC3, go to local network and alt+tab out to find out which key is currently installed.
As for the disconnecting thing: This is a common issue, sometimes it also happens to me, but then i just close warcraft or restart my pc and everything is fine. Also if you push the BNet button very often sometimes you can logon without restarting warcraft/your pc.
I assume the BNet-servers first have to recognize that the player has been disconnected and then delete him from the "online list". It might take some time, but usually after a couple of minutes you can logon again.