Software should absolutely try to account for these kinds of errors and routinely does. When was the last time you saw a word processor or spreadsheet bork a machine so hard it needed to be restarted just because an AV scan kicked in? ReadFile and ReadFileEx both hand you a specific error if some part of the file you are trying to read is locked by another process because it's hardly rare. 'Halt and catch fire' is not generally considered a proportionate response. I've no idea where you're getting this 'unplugged the disk' thing from, AV software does not work this way.