Typing causes blank screen

My new HP Envy Touchsmart 17 m7-j078ca over the past few months has been intermittently experiencing a blank screen when I type. It sometimes freezes or it goes into sleep or hybernation mode. Once this starts I have to reboot to get it back otherwise each key entry causes it to go into sleep mode or a blank screen. Swiping the mouse pad or hitting the power button allows me to see the screen but I have to resort to using the onscreen keyboard to do any further input. It is very annoying and frustrating.

I use this Envy infrequently - weekend evenings mostly for light personal use so I havent had the time to investigate this further. It is right now acting up as I type this so had to resort tomthe onscreen keyboard.

I have updated drivers and bios to no avail. my problem ismsimilar to this post

http://h30434.www3.hp.com/t5/Notebook-Operating-Systems-and-Software/dv9500t-and-g7/m-p/578641/highlight/true#M58482

any suggestions or recommendations is most welcome.

thanks

sj60