Antivirus found Trojan Exchanger.UT

[GlassFish]

My antivirus has detected Trojan Exchanger.UT. It is a trojan virus. I am using a free version of AVG. How this virus enters a system. Once infected how can I remove it. My PC is working very slow. This virus comes in mails. After that there is lot of junk mails coming in my inbox.

[Big Fish]

Exchanger.UT program is a malicious Trojan horse. It comes as an email attachment without having the appearance of a brief news transmitted by an associate . It is very important to ensure you apply the preventive measures
listed above to prevent reinfection of the computer. It is a trojan type virus.

[Shen]

The virus has lot of different names. I am giving all the names if you found then delete them. Also scan your computer. The names are TR / Dldr.Exchanger.AH, I-Worm/Nuwar.V, Trojan.Downloader.Exchanger.Gen.2,
Trojan.DownLoad.4242, rojan-Downloader.Win32.Exchanger.ut, Tibs-Packedl, TrojanDownloader:Win32/Cbeplay.I, Win32/Agent.ETH, W32/Smalltroj.GDND, Mal/EncPk-DA, Trojan.Erotpics, etc.

[Steve123]

The virus comes from email. The sender of the message is a spoofed email address or generated automatically. Some examples of title of message are : Surprising! Please take a look. Breaking news! Be the first to know, Check this out, This is a bomb!, Sensational news, Check the message, This is really great news, Please check and Very important news.