|You said it is a trojan.|
Try Trojan Remover and Hitman Pro, if it is a trojan they should remove it.
Another thing to try is Avast free. Unload AVG and do a bootscan with Avast. It will probably remove the problem as it is much better than AVG for removing viruses, etc.
Some HELP in posting on Computing.net plus free progs and instructions Cheers