VIRUS w32:trojan-gen {---}

Hey I Have A virus in a chest on my computer
and i cant get rid of the virus its in the chest which is kinda a good think until it escapes so i need a update or fix for this virus

IS it even a virus

ever since i got ALWIL Avast 4 Antivirus
when i send mail which attachments it always says suspious letter do u wanna send
if i say no the message dont get sent
if i say yes the message gets sent and i recieve a virus somehow it really weird
is this a virus or wot

or is it just an error called that
i dont know thats why the points are high high high

I NEED HELp
i dont wanna format again

i have had 2 viruses in the last week and i cant deal with other thanks