Trojan Help! [Details Below]?

Hi there,

My sister and her "friends" were using the computer for "homework/research."

Well when her "friends" left, we found 2 trojans on the computer! We are using Windows Firewall and an up-to-date version of NOD32. Automatic updates and registry cleaner too.

One of the trojans was quarantined and deleted [both in log and the IMON (internet monitor).

The other trojan was quarantined (i think deleted too?) in the AMON (file monitor) but on the log page there was an error.

The one that has an error was something as: "HTML/TrojanClicker.Agent.F Trojan" from scanner.spyshredder-scanner.com/...........

How can I ensure this trojan is off of the computer? And also, what exactly does this trojan do and how do you think my sisters "friends" got it on the computer?

Also, what's a good FREE anti-SPYWARE program that's good for getting rid of spyware, cookies, adware etc?

Thanks.

Trojan Help! [Details Below]?symantic

Don't go thinking the worst of your sis' friends. Trojans can be picked up anywhere; Myspace, Facebook, any P2P file sharing. The effects of trojans are varied. They can run from simply annoying pop ups trying to get you to buy bogus products; to malicious programs that can literally take over your computer.

NOD 32 is definitely an excellent antivirus, but I'm not sure what the error meant. If by chance it didn't completely remove the SpyShredder (mentioned in the error), you can run this removal procedure here that has a link to and instructions for running the smitfraudfix.