In the last week, my iLiad has switched itself off three times for no readily apparent reason, while the battery was pretty much fully charged. I got the closing down screen, then a blank screen, but the green light remained on. The on/off switch didn't work, and pressing the reset button started it rebooting.
I sent in a support ticket to iRex this morning, and I've just had a reply that they want me to send it back, and they're sending me a box to put it in.
Luckily, I've only had it since February, so it shouldn't cost my anything.
I suppose at least I'll get round to reading all those dead-tree books on my readpile that I've been neglecting...