As noted, this popup was static and no interaction was possible in any way (with the exception of grabbing and moving it around the screen): no resizing, no hover reaction, no button functionality – nothing. The computer could be used normally in all other known aspects, but no other information was obtainable and the only way to close the window was to shut down avast! completely. I conducted a thorough file/registry search for the available object ID but found no matches across either of two user accounts.