Hallo,
warnings have no implication of infection - it's just about why the file wasn't scanned thoroughly (inaccessible, unreachable, whatever).\
they are in cyan. what's important are the real viruses - in red. delete them using avast's toolbox-button, or, open their location in finder (use "reveal in finder"), and manipulate them from there.
bnote: not all files could be manipulated. some are inner part of solid archives, and you must manipulate the file as whole (in such case, the parent-file is shown too, above the finding).
regards,
pc
