Thanks for your reply. I have some questions:
1. In your item #2 you say to schedule a boot time scan and if Avast does not detect it then try DrWeb CureIT. I don't understand. Avast has already found the virus. How can it not find it again?
2. You say to try an anti-rootkit program. But doesn't an Avast scan include checking for rootkits?
Tech is speaking generically and not about your specific issue, so hopefully it would detect it and be able to deal with it on the boot-time scan. If either of those doesn't (detect or be able to deal with it) then you go to the next option. This is not saying avast won't find it if it has previously detected, but a series of steps.
A multi-application approach is often more effective (and again are just a series of steps) than one single application detecting everything, which can never be guaranteed to be 100%.