OK, I'll give it try: There is more than one way to deal with this situation.
First of all: If you haven't done it yet: I recommend to backup your data. (Rescue as much of it as possible.) Don't forget to scan your backups for viruses later and/or do another backup when you have finished cleaning your system.
Apart from that:
(1) Ensure that your system is clean. Try to boot it from a disk that is known to be virus-free and which contains an up-to-date virus scanner. That's easier said than done, because sadly I don't know any source where you can get such disks for free...
If you have access to such a disk and you have either cleaned your system or made sure that it's already clean than you're fine. Either try to repair avast or uninstall and re-install it.
(2) If you are not able to check your system from a clean environment than you might want to check your system with another virus scanner like bitdefender free 8 or some other on-line-scanners.
If you have either cleaned your system or made sure that it's already clean than you're fine. Either try to repair avast or uninstall and re-install it.
(3)As far as I know the most secure way of cleaning your system is to delete all partitions and perform a complete re-installation of your system. But I guess you don't want to do that, and it is not allways necessary. Doing this would mean that you delete ALL your data, so be careful! there might be other ways to solve your problem. This option should be your last resort and you should first listen to what other people might recommend you.
As I said: Before using your backups make sure they are clean, too.
BTW: "Residual" means something like "remaining" or "the rest" of something. I think words like "provider" or "resident scanner" are more fitting in this context.
