Has your Ti 500 just come promptly back from AppleCare with a nice, new case (to take care of paint bubbling and worn-off rubber lid stops), two new rubber feet (to replace the ones that had fallen off), new keyboard (to fix a broken "period" key) and new logic board (to replace a non-functioning FW port)? If so, don't call AppleCare and endure the long, annoying music-on-hold to ask how to remove the dark-purplish ink-like blotches someone sloppily left on the lid near the latch. They'll only tell you, after leaving you on hold for an even longer time, to use a soft cloth and nothing else--which, from my personal experience, even if you use with KlearScreen and a lot of very hard rubbing (not particularly recommended on the back surface of the LCD) may take you oh, say, at least three or four hours for an area a quarter the size of a dime. They'll also tell you that you can go to an Apple Dealer who will remove the stain for you--but they won't tell you what the Apple Dealer will use to do it, so you could do it yourself. Instead of wasting your time doing all this, get a bright inspiration to try a Staedtler vinyl eraser. Two or three seconds of gentle rubbing and instantly the stain will disappear, with no damage to the case. At least that's what happened to me. Use at your own peril--I assume no liability! David