I know that you've experienced this a few days ago from my routine Googling but didn't know you haven't find a way back yet.
As from your original post, you were using Webtop at that moment and all in a sudden with the HDMI cable unplugged, then the phone rebooted.
At least a panic log is needed to verify whether this is related to Nebtop, or the stock ROM+Webtop.
As Nebtop has no listening of the HDMI cable plugging/unplugging event, it should had done nothing at that moment.
And your current state sounds like the file system is corrupted. If I have no way to fix this, I would try to backup the current state first, then try to revert to the stock. (not sure if Atrix 2 has any stock image leaked
Finally, I'd like to help to identify the actual cause of the reboot, only if you could look up the kernel panic log at this location /data/dontpanic/apanic_console (this is the path for one of the Motorola phone, it could be changed for Atrix 2).
Originally Posted by mlo0352
Just a word of warning:
This app totally screwed up my phone. I installed it and was using it just fine for a couple of hours. Then all of a sudden, the phone becomes unresponsive. I unplugged the HDMI cable, and it rebooted. I didn't think anything of this. Just found it a little odd. Since then, any time I reboot the phone, it is reverted to the same state it was in right before the crash. The text message I had not yet read is re-received as new. All app updates are reverted. All new apps aren't installed. All new texts (since then) are gone. Apps are force-closing left and right. Be VERY careful with this app. I'm not sure it's really ready for prime-time, even now.