I have read multiple posts about members having random unresponsiveness with the Nexus touchscreen, sometimes being fixed by sleeping and then waking the screen. I have found a cause and solution to this problem.
The problem is with the touchscreen controller (AMTEL MXT224) driver (/driver/input/mxt224.c) by Samsung and it not sending calibration signals for the touchscreen. Yuanjie has created that increases the threshold of touch, decreases the threshold of noise, and forces calibration after resume.
Unfortunately, this patch must be applied to kernel source code, compiled and flashed via ClockworkMod Recovery - so if your phone is not unlocked and rooted with CMW then this will not work for you. If you have ClockworkMod Recovery on your phone, and would like to try this kernel, you can find it on . It is the with his patch applied. It works fantastic for me, however the values in the patch may need to be adjusted if your phone does not respond well to the included values. I can't help with the adjustment of values as I have had no need to change them since the current values work for me.