I think it would definitely be a trojan if they have hijacked your mouse and keyboard. One such of these iss Back Orifice 2000. With this they can send commands to your box, hijack control, or even reroute their data through your comp to another even without yuo knowing of it. You can get rid of these sorts usually with a goog Virus scanner which has been regularly updated, and if that still doen not work I seriously suggest to have a look in your registry under the "run" or "runservices" key which can be found on most comps in "hkey_local_machine/software/microsoft/windows/currentversion/ *run* or *runservices*.

Invest in an Intrusion Detextion System like BlackICE from Network ICE. this will detect and block port scans, intrusion and other such unwanted activity. www.networkice.com

And if you still cant do anything maybe stop using aim or get a different browser or just DONT USE WINDOWS if you are. Also you might try dropping to dos while you are connected and type in "netstat -a" i think it is. this will get you the ip addresses statuses and ports of incoming and outgoing data. Here you can see if someone is connected that shouldnt be. Or ithink another one is "arp" to do this.

Hope i was some help. Keep trying.