I never had this problem on Verizon stock 6.1 ROM... I now am on Verizon stock 6.5 and have this happen every once in awhile... I have been switching back and forth on internet browsers... and I noticed the only time this happens to me is if I lauch the new internet explorer in 6.5 ROM and leave it open... it does not happen everytime, but maybe 50-60% of the time... yesterday IE was open, and I used the top button to turn the screen off... it then would not come back on... kept hitting the button and then held it down for about 10+sec and it eventually came back on... who knows...
Just one piece of software I now close/exit all the time...