Help!!

Hey guys
Today, after driving for about 3 minutes, I stopped and went to make a u-turn. When i did this the power steering stopped working, and the whole dash board (steering light/check engine/etc.) all lit up and then went away again. I have a had a power steering leak for a month or so, but it has never gone empty. I replaced the o-ring but that did nothing. I think it may be in one of the lines. I am just curious as to if anyone has ever had this happen? And what would the flashing of the lights indicate? I checked the fluid in the pump and it seems to be at a good level (I topped it off just for safe measure.) I have turned off the car, and left it for about 2 hours, started it up and turned the wheel (while stationary) and the same thing happened - power steering cuts out and the dash board lights up.

Any suggestions would be appreciated.
thanks
Jonesy