I have had a regular evo, a replacement, and now have a 3d evo. All have rebooted randomly. My first one didn't do anything for about six months, then started doing it every few days, it seemed like it was when I was away from home, usually using apps. Then it started when I was on the phone too. I finally took it in when it it was happening just sitting in my pocket, and constantly rebooted until the battery was dead most times. The person in the store did a hard reset, and it never stayed on again. He ordered a new one.
New evo a week later. I was offered the $150 upgrade in advance, so I ordered a 3d evo. In the three days it took to get it, my "new" evo rebooted a few times randomly. (I had to use it until I got the 3d)
Queue the 3d evo. It rebooted on the way home from the store a few times. I took the battery out, waited, put it back in. Started up again. Still randomly reboots at least five times per day, sometimes flashes to "htc" screen and then says "loading" and comes back to the home screen after 10 seconds. Mildly annoying. Just sitting there, using apps, exiting internet, wifi on/off, no 4g access here, so I never have that on... totally random.
I love the phone itself, but come on, three phones with the same issue?? Frustrating!!!