Something I've always found confusing is when a progress bar jumps backwards a little. Like did the computer just undo some of the loading?,(reply>), I regularly use a machine that counts up to 104% complete before jumping back to 100% and finishing. I've always wondered what's in that 4% extra that it claims to be doing above and beyond what was asked of it?,(reply>), It's when the computer tried to predict the future to make the progress bar smooth, but it failed miserably (overshot) and has to correct its answer.