I also had this happen, it was due to a windows service not being loaded on startup, but the fact that it effected Avast is really bad as it could be used to prevent avast from being effective on the machine.
I borrowed a firends connection to get a big download, and when I booted up to the desktop I had this error in avast, along with no connectivity. Well I had disabled the dhcp service as I never use it normally, and when I enabled it everything was fine. However due to Avast's dependency on rpc, AVAST FAILED due to rpc not being able to contact the dhcp service.
The fact that Avast depends on RPC is a very possible local security exploit.