help! MacBook Pro video/screen issue

13" MBP bought Sept 2011

running 10.7.3 Lion, all updated

- screen going black spontaneously

- cannot discern any cause

- brightness controls do not help

- like it goes into sleep mode spontaneously, but won't wake up

- screen brightness *does* fade out (quickly) - does not cut instantly

- if I tilt the computer a few directions, sometimes it comes back

possible loose connection somewhere?

or known SW issue?

thx for any info!