When i put my mbp in clamshell mode to use my hp2311x monitor it wont work. i try to wake up the computer for sleep with mouse and keyboard. when i do it says monitor going to sleep over and over again... and if i try to open the mbp every 5 seconds the mbp screen turns blue like 2 seconds. this happens excactly the same time as the monitor says monitor is going to sleep.

The thing is it worked fine for 2months and now its not working

plz help!!!!