This is my second MK850 set,
1st one sent back within 4 months since spacebar stopped working after few months. Now this 2nd once again only 4 months old; 'p' button and '1' button which switchs the keyboard to other machine do not works only 25% of time. Shift P also do not work most of the time.

I like MK850 tech and keyboard sucks after spending so much money for this, I feel very disappointed in logitech quality.