Recently I've noticed new niggles with my Xperia X10i, which I can't figure out.
While charging, the phone will turn on the display for no reason. Note this is after the default "turn on when plugged in" behavior. It will be sitting there nice and quiet, and then bang - on comes the display. Weird. And no, it's not an alarm. Could be an email, I suppose, but I have the email notifications turned off.
The phone will also reset itself for no reason. Same thing - just sitting there - and bang, I see the Sony Ericsson logo/splash screen come up. Don't touch it or anything. Doesn't correspond to a phone call, SMS, or anything else I can identify.
It loses the Bluetooth connection sometimes. I thought the first time my band-new BT headset was already busted, but it turns out the phone needed a reset. Voila! Back to normal.
It also, very occasionally, fails to auto-rotate the screen. Turning the phone sideways doesn't change the display to landscape mode any more. Reset, and the normal behavior returns.
Some of these I attribute to Android - it's just immature, and doesn't handle problems too well in some cases.
If anyone knows why these problems occur, I'd like to know too.
[p.s. - By the way, people, it's spelled "voila", not "walla". Seriously, get an education. And no, I'm not bothering to figure out how to show the accent in Blogger - shoot me.]