Avast 4 Home Edition Crash

I recently downloded "Anti-Trojan Shield"and I believe it caused my “Avast 4” program not to work anymore. I do get the splash start for memory test but the program will not continue. I have turned of all anti-virus software (McAfee) and “Anti-Trojan Shield”, but it still will not run. Any advice? I do show 1 running On-Access Scanner.

Do need to download avast again and reinstall, and if I do will I lose the files in virus chest?

I have been trying to repair my files (winlogon.exe), which is infected with win32:Troajn-gen {UPX!}, any help there.
Avast identified it but did not repair it. At this point I do not want to delete it, because I do not know how it will affect my operating system, and I’m afraid to reboot. Please help.

Thanks in advance.
Nitro

Please do not open/write two post with the same problem in different threads. Look here: http://www.avast.com/forum/index.php?board=2;action=display;threadid=1056;start=msg5762#msg5762