I'll report the same or similar problem on my Lenovo Thinkpad P540P using 14.04. New kernel 3.13.0-48 broke my USB mouse and my Wifi Connectivity. Keyboard still worked though, but I am using an internal laptop keyboard rather than USB one. Reverting to 3.13.0-46 "solved" these problems.
I'll report the same or similar problem on my Lenovo Thinkpad P540P using 14.04. New kernel 3.13.0-48 broke my USB mouse and my Wifi Connectivity. Keyboard still worked though, but I am using an internal laptop keyboard rather than USB one. Reverting to 3.13.0-46 "solved" these problems.