Cannot Drag down cells even though its turned on in Advanced options

[PontusLindholm2010]

I'm an experienced user and I'm used to be able to solve issues on my own, but this one has stumped me. I would appreciate any help and suggestions.

While was working in a Excel spreadsheet I can suddenly no longer can drag down cells. The cursor simply never turns into the plus sign. 

I have triple checked the Options-Advanced-Drag down cells, it's not the issue. Also tried to reset it back and forth, not working.

This no longer works in any workbook. Also restarting my computer didn't work.
I have also turned off all COM addins to check for conflicting issues.

[#2]

Okay I found the solution, from another post on here. The problem is the docking station causes a graphical bug with the mouse cursor. I plugged it in and out and it started working correctly.

This is quite bizarre since even though my keyboard is connected to the docking station my mouse is a bluetooth mouse.