What is this?

[Kaushik Dash]

So I turned off my phone and before it could restart itself I plugged in the charger and this is what showed up.
http://i57.tinypic.com/4gp4dw.jpg

I just checked my email before that, did nothing with the settings or whatever. On removing the charger, I was able to turn on the phone to normal state.. What does that sign mean?

 

[Pete]

It means the phone has crashed, a soft reboot usually fixes it.. Looks like you got it sorted though.

Read here for an explanation.

Your Windows Phone 8 doesn't work or respond as expected

 

[shmsnh]

According to Microsoft, that appears when the phone is unresponsive.

 

[Kaushik Dash]

Quick reply, thanks!

 

[ShreyansShah]

ok. that means finally, microsoft have found a new BSOD.