My Eris has a scrolling issue which is very annoying. Often occurs while browsing as I am usually scrolling slowly with my finger, whereby it will on occasion begin scrolling at full speed, like a slot machine.
I know I've seen this issue mentioned before, as I read about it when I first got my Eris with 1.5. My device was problem free until a few weeks into use when the 1.5 OTA update came around. So this is an issue which started on my device in 1.5 and continues into 2.1.
I've tried Multitouch Vis Test and it seems to work fine, no jumping around or anything. So I cannot say with confidence that this is a hardware issue. What I suspect is that they compute the movement in such a way that it gives oddball readings when the device may be laggy.
it's not that the phone gets oddball numbers at random and says idk what to do lets scroll fast...
But you are correct the phone lags and what happens is when it lags like that it thinks you just moved your finger farther and faster than you did
Think of it like this. Your scrolling slow... lag lag lag... but you continue moving your finger. When the phone catches up it says ok so your finger just moved from point A (before the lag) to point B (after the lag) in 1ms so that must be a fast swipe... and than ZOOOOOOOMMMMM off it goes. It's a pain in the *** but there isn't much you can do about it.