Trackpad - single finger resting selects the item where the cursor sits

Recently without any upgrades or new software loaded, I now find that when I use single finger on the touchpad (without pressing - just touching) and if I hold my finger for more than two seconds and then remove, the item that the cursor was on is selected. This is just as if I was pressing the touchpad but only if my finger is held for more than the two seconds.

I have read on here to change the "point & click" options within system preferences/trackpad and then restarting, this appears to have fixed the same problem for everyone else but not for me. I have tried with tap and click on and off (currently off).

Any ideas?

I am running a mac book air 11" mid 2012 with OS X Yosemite 10.10.2