To the second quote. If you CHOOSE to continue access the file of course you should be able to. But when you choose "Delete" (or another choice to remove the virus) then there should be no way for that virus to get active.
Now, we don't exacly now what happened. But say that when we pressed "Delete" and avast! gave the error message about not being able to delete the file, that the control then was passed back to the system making further execution of the infected file possible - that would be bad.
The only way an detected file should be able to be executed should be when the users answers the virus alert message with "Continue access anyway" (or something similar), right?
BTW: Just to clearify, this IS one my home PC (but there are not only me living here, I'm a developer/tech, I know what not to open, I could have lived without an anti-virus - I think anyway :-)
My system is a Win98se, avast! resident scanner, Zone Alarm, and I'm connected to the world through a cable-modem.