Help, avast won’t start anymore. I’m using XP Home and avast! Home Edition 4.8.1195
Yes, it is set to start automatically in Services…
Fixed!!! 
I did the Repair a second time and it avast! started after the reboot. Weirdness… but happy! ;D
I just posted another thread about this, I didn’t see this thread or I would have just replied here. I too have this problem, but repairing and restarting multiple times haven’t helped me yet. Any other thoughts?
The RPC error can also be associated to either another AV installed or remnants of one previously installed.
Have (or did) you another AV installed in this system, if so what was it and how did you get rid of it ?
Nope, never had a previous version of Avast or any other antivirus on this computer (save for about 30min ago after it failed to start and I uninstalled and reinstalled).
Have you checked the other things in the F.A.Q. ?
Namely that the avast services is set to automatic and is running.
AAVM subsytem detected and RPC error. http://www.avast.com/eng/faq-other-questions.html#idt_1539
I take it there is also a Red circle with bar over the avast icon ?
Yes, I have checked the FAQ and looked at the services. It is set to automatic but it is not started and when I attempt to start it, I get “Error 5: Access is Denied”.
That is interesting why access would be denied, I know that the new self-defence module protects avast from being shutdown, etc. I would have though it wouldn’t have objected to being started.
Are you logged on as a user with administrator privileges and not as a Limited User account ?
Try disabling the avast self-defence module, Program Settings, Troubleshooting and reboot.