Flash intermittent problem

[dlw]

I just purchased a '99 Explorer and love it but today had a small problem. I am a landscape photographer and often have to park along the road and get out to shoot pics. Today the hazard flashers would work for awhile, then the lights would stop blinking and both front and rear lights remained on but not blinking. My turn signals also stopped flashing and just gave a solid light. Each time this happened, it would operate properly later. I think its the flasher unit and would like to know where it is and any other ideas if this doesn't help.
Thanks, Dan