Avast! heuristic

when the heuristics of avast detect suspicious files in the computer, it indicates me that the recommended option is to ignore. Then it indicates me that there is virus in the memory and recommends to me to do boot time scan, but it gives the coincidence of which he does not find any infection.

What is the idea of this process? it has happened to me 2 times.

Note: I solved it doing a restore point