Which thing did you do that initially seemed to work?

Sounds totally like your isp to me. And it sounds like a p2p shaper program they use. It detects your program & then takes action. That's why your few few moments are ok until their program kicks into action.

Try BearShare Lite to see if you suffer the same problem. If yes, then it's the isp at fault. If no, then either the isp is only targeting LW or else the problem is elsewhere. http://www.filehippo.com/download_bearshare_lite/

If youe incoming is false, then that means you're firewalled. Make sure your firewall is properly configured. Also make sure your modem/router's UPnP options are turned on. If it doesn't have UPnP abilities then manual port forwarding is the go. See Connection problems? Check here first! (click on link) which covers all the points in this particular paragraph!!!