I was in BestBuy last night killing some time and saw they had a new XA2 on the shelf. I had a 10% off coupon with me and made an impulse purchase (I was going to get an A35 but what the heck). I picked up a couple of HD-DVDs and brought it home. Every time I try and play an HD-DVD, the unit shuts itself off at random times, but never plays for more than a few minutes. The strange thing is that it plays standard DVDs just fine. I updated the firmware in it hoping this would make a difference, but it does the same thing. I guess I'll be bringing it back today and if they have another in stock I'll exchange it.
I did see a report on Amazon where someone else reported the same thing, but it doesn't look like a real common problem. Just my luck.