That's very odd. I assume we're talking about the same computer here, which can see the empeg via ftp/http but not via emplode, at the same time (i.e. no reboots in between)?

This would not be unusual if he had firewall software such as the XP personal firewall, BlackICE, ZoneAlarm, etc., running. Those would allow Hijack HTTP but not emplode. Again, covered in the ethernet troubleshooting tips here.

Also, I would think that if the player were on a different subnet than the PC, that HTTP would work but emplode would not. Also covered in the troubleshooting tips.