I used my dryer on timer setting this morning. Once the dryer stopped, I tried to set it for another few minutes but now the dial just spins (doesn't seem to be catching on any settings) and the dryer won't turn on.

Check for an Allen screw that needs to be tightened. Look here: https://dl.dropboxusercontent.com/u/8010163/GE_DryerTraining%20GE.pdf
https://dl.dropboxusercontent.com/u/8010163/GE_Dryer%20Training%202.pdf
https://dl.dropboxusercontent.com/u/8010163/GE_Dryer%20Training_MINI_MANUAL_091109.pdf
https://dl.dropboxusercontent.com/u/8010163/GE%20Dryer_Training_31-9136.pdf
If you do not see a screw you will have to examine it carefully and look on a parts site to see the matching knob and how to install it.