Same issue hear. Checked with two other RAZR users and they also have it, though not as frequently as me. Mine seems to do it 2-3 times a day.
So it turns out I was wrong about what I thought was causing the issue, but now I'm 99% sure I have isolated the problem. It has something to do with charging the phone via USB, or more specifically connecting the device to a computer system. After attaching the phone and letting the display time out or sit for a little (screen may still rotate while attached) it seems to "fix" the screen in the vertical orientation. I have no idea why though...
I have been using the wall charger for about a week now and the screen rotate has been working fine. My phone hasn't been rebooted in over a week and I've been using all of my apps regularly. Before it wouldn't even last a day without the screen rotate becoming locked so I'm going to say the source of the problem is USB connection to PC. I can't say if this is a desktop OS, mobile OS, or USB specific issue but it seems like for whatever reason connecting the phone to my computer causes the bug.
Once the boot sequence is finalized, when you reach the homepage you'll see in the bottom left hand corner the words safe mode.
The phone will function normally in every sense of the word except that you will not have any applications that were user installed available in the app tray, although some may appear on the home screen and will work from there. Also, no widgets will be available except for factory installed widgets.
To revert to normal boot at anytime simply power the phone down and power backup normally.
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