[ol]- Today Avast put a file there, and C:\$AV_ASW folder was created.
I deleted the file (in Avast) from the Quarantine, so the Quarantine is empty again. Then I restarted my computer.
But, the C:\$AV_ASW folder is still there. It contains a single folder $VAULT, which contains a single file vault.db. Size of the file: 1,622,016 bytes.[/ol]
I believe it is the Virus Chest - I have one old detection In Quarantine - that I keep, more for screenshots relating to queries in the forums. However I have 4 .dat files and the vault.db file.
I would imagine that that folder would be protected in the same way as other Avast Program elements (I have never considered trying to delete it).