08-22-2016 09:47 AM
Just to give some feedback after quite some months.
Contrary to what I believe before, I can confirm that it was also a *hardware* issue for me. Lenovo support has replaced the screen with no additional operations that I could find on the OS, and the touchscreen is working 100%. (versus about 20% of the time before that)
All software upgrade did nothing (bios, windows patch, OS reinstall, driver tweeking etc...)
So if the touchscreen completely stops working on a random basis after a reboot (but not necessarly the pen) i would advise to send it for repair.