Keyboard and Mouse Stopped Working

Arrived at the office today to find the keyboard and mouse not working (partially):

Mouse moves, can't click on anything. Using ARD, to get in system preferences reports no mouse installed.

Keyboard works during bootup to enter credentials to decrypt drive. Once OSX loads keyboard no longer works (can still light up caps/num lock).

Same keyboard works fine on another identical system.

Working keyboard and mouse from other identical system do not work on this one.

Mac Pro 4,1 8 core.

OSX 10.10.3

Nothing appears to have updated since it last worked (yesterday afternoon).

Any ideas?