"There is a known problem in After Effects CC 2015 (13.5), but only on Mac
OS X, where the Hand tool does not work in the Timeline panel but only
when you are using multiple monitors, the Timeline panel is on the
secondary monitor, and the secondary monitor is positioned to the left of
the primary monitor."
I am on Windows 7 with a quadro k5000 card and the problem is exactly as he described. I let them know it's a windows problem too.