Lumia 920 power on delay

[Bicpug]

I had to reinstall my lumia920 and now when i click the power button the screen lights up, but no touches register until after a few seconds when the screen dims slightly then i can slide to unlock....then the phone works as normal, the touch used to work immediately. Is this known about and is there a fix?

 

[shmsnh]

Are there apps running in the background? I've seen this issue once or twice on my old Lumia 520, and it was usually some rogue app.