Sadly, my slim 360 (just over a year old, fairly light use) came up with an E64 error recently. I had traded in my launch 60gb fat (still working perfectly) for the slim 250gb when GS offered the huge credit, and thought I'd be set for a long time. Now I'm thinking that the last generation of fat XBox systems (with Jasper chipset) is probably more reliable than the slims. I do have backup Jasper systems still new, but didn't want to give up on a fairly new and supposedly reliable slim. So I paid the $100 and sent it in for repair.
Fortunately I have plent of other systems to play, but its a bummer that such a new design would crap out after such a short time; particularly considering it wasn't heavily used (never left on, always put away after playing in a padded backpack, to keep the cats from chewing the cords or whatever!).
I understand that all complex electronics products are subject to wear-and-tear, heat damage, etc. but its pretty disappointing that such a new design would crap out so quickly.