I've scanned my system a few times this week and on each occasion the scan has picked up 4 threats (trojans)

When I go to delete the threats, the system simply hangs.

I've disabled Zonealarm and no other programmes are running.

I'm using XP

Any help would be appreciated.

Greetings and welcome to the forum. To get you fixed up please read the instructions here: http://www.malwarebytes.org/forums/index.php?showtopic=2936 and post your logs here: http://www.malwarebytes.org/forums/index.php?showforum=7

Please be sure not to install any software or use any removal/scanning tools exept those that you are instructed to by the expert who will be assisting you as doing so can make their job much more difficult. Good luck and safe surfing.