If avast's standard shield can detect it then so too should the web shield, which is also true if it is coming via P2P or Instant Messaging, assuming your P2P and IM programs are supported. These scanners provide an earlier detection before it arrives on your HDD this makes it easier to deal with than if it gets established on your HDD. Your IM and P2P program may also allow for the direct scanning of downloads, if so then this is the file to use, C:\Program Files\Alwil Software\Avast4\ashQuick.exe.
Do you have a firewall, if so what is it ?
It could be possible that there is a trojan on your system that is downloading this or creating a backdoor to allow access.
Not all files can be cleaned, Trojans generally can't be repaired (either by the VRDB or avast virus cleaner), because the entire content of the file is malware, so it is either move to chest or delete, move to the chest being the best option (first do no harm). When a file is in the chest it can't do any harm and you can investigate the infected warning.
The VRDB only protects certain files, .exe, dll and other system files, it doesn't protect data files or all files, it is not a back-up program, so there are going to be many occasions where repair won't be an option.
Only true virus infection can be repaired, e.g. when a virus infects a file it adds a small part to it, provided that file is one that avast's VRDB would monitor and you have run the VRDB, then it may be possible to repair the file to its uninfected state.
However, for the most part so called viruses, trojans (adware/spyware/malware, etc.) can't be repaired because the complete content of the file is malicious.
