Ignition Switch Issue?

My 2008 Tacoma is having intermittent starting issue. I've noticed that when I turned the key to "Acc" the radio power, clock, power window all comes on as normal. However, sometime when I turned to "On" the power to the accessories cut out (radio, clock, power window), no power to the heater either when the switch is on, the warning light on the dash are on however. When this happens my truck would not starts; I would have to try few times before it power up and starts normally. Any body has the same problem? Do you think it is the issue with the ignition switch?