Okay.. so Avast! found adware and a trojan horse in the C:\Soundsettings bit of my computer, can i ask is this possible? and if i heal the file will it muck up my computer?

Quote from Fredthebest :

is this possible?

Yes.

Quote from Fredthebest :

and if i heal the file will it muck up my computer?

Shouldn't do, but without know exactly what the file and path of it was, you can't expect a certain answer.

also if Avast! moves the infected stuff to the virus chest, does that mean that it is removed?

That depends highly on the virus. Some require you to just delete a file, but some of them are much, much, deeper.