when using the explorer context menu to scan a folder or a file,
Avast create a scan task with "?" as name ...
after you cant delete this task ...
is this a bug ...?
If you are referring to "
?" appearing in the pull down list of scan types (Avast UI->Scan) then from memory this could occur when Avast 8 was updated to Avast 2014 from within the program. I think the link to it occurring after a context scan may just be circumstantial.
You could try a repair first, but if I remember correctly the best way to fix the issue is to uninstall the existing Avast, clean up using the Avast cleanup tool, and do a new clean install.