I need help....Avast don't want to scan for virus

I need help

Avast can’t run a scan for viruses, my computer freeze after a few minutes…And I’m sure I have a viruses. What can I do to remove the viruses

thanks and sorry for my english

Can youdo a boot time scan ( see link ) When the memory scan begins,stop it,then proceed to try the boot time scan
http://www.digitalred.com/avast-boot-time.php

I try it. But didn’t find anything and my computer still froze after a few min. What else can I do?

You can try Avira rescue cd. You may need another pc to download.When you download the file,double click on it,you will be prompted to insert a cd,the program will be burnt to disc.Inset the disc into " infected " machine and reboot.This program is fully updated and does not load windows.
Your problem may well be elsewhere and not virus related at all

CD instructions http://forum.avira.com/wbb/index.php?page=Thread&postID=730130#post730130

Avira rescue cd http://www.free-av.com/en/products/12/avira_antivir_rescue_system.html

Why are you sure you have viruses, Germa?
What operating system is it, and what other security applications are installed?
What AV was installed before Avast?