Abusing progress bars are not a good response to this, though. I would rather trust progress bars for what they are meant to show rather than as an indication of true activity. After all, you still can't tell whether the progress bar kept moving, but the process is stuck in a loop.
The problem that people might assume the computer is stuck in a loop or at any rate that the animation is not going to stop is related to spinner animations on websites. Since the spinner is not a function of the browser, but is instead something implemented in the individual site's code, then stopping the spinner needs to be also coded for and many sites neglect to write the code for "when error happens stop spinner and tell them that things went wrong".
So over time people exposed to negligent website spinners start to suspect any spinner that takes too long.