Installed Avast and my computer keeps logging off when I sign in, HELP!

That was the first time I have installed avast on that computer.
The virus has comfortably been sitting on the specific computer for about a year, Avast was installed today and the computer then goes funny. Maybe Avast triggered something, I’m not sure. All I know is that I try to log in and it logs me out straight away so I can’t even sign in to try to fix anything.

Can it be fixed???

If worst come to worst would it be possible to extract the files from the hard drive?

Please attach your logs.
http://forum.avast.com/index.php?topic=53253.0

Please attach your logs.???

what does that mean?

It mean’s attatching the neccesary scan logs which you will be instructed to run when you read the link in Asyn’s post.