+1, and I did just that...returned my first Vivid for a second...but unfortunately the results are starting out the same.
The last straw with my first Vivid was that it got into a continuous reboot loop and drained my battery from 85% to dead in like 10-15 minutes. I plugged it in with the charger, and accordingly to the HTC battery widget, when it charged back to 100%, the battery display at the top right of the phone showed an empty battery with the exclamation point. Seemed like a bad sign and given the random restarts...I took it back to BB in exchange for Vivid #2.
Vivid #2 started off better...over the first 36 hours, it charged faster than the first and seemed to hold the charge overall better on its first two drain cycles. However, last night, 48 hours in, it randomly restarted three times within 90 minutes. The first two occurred when I pushed the power button to wake it up, but the third time it happened just sitting on my nightstand.
I so want to like this phone but...not really interested to have to worry about this. My 30 days at BB is up next Tuesday; that'll give me a chance to look at the Nitro HD but quite honestly the 3 hour talk time listed on LG's site for the phone and even supposedly worse battery life makes me very nervous about switching to it.
Regardless, I have at least 4 more days with Vivid #2 so I'll continue to keep an eye on the restarts and post back should I notice anything more detail as to the cause.