Shuts off at slow speeds

I noticed that my vehicle will shut off on me when I am driving at slow speeds like driving out of a parking lot. I lose all power like the battery just died but the battery is brand new, it just quits. I lose all power steering, it is like no electricity is running though it at all. I have seen other posts on other sites about people having similar problems and they said something about the ignition switch not connecting because of too much weight on your keys. But I do not have hardly anything at all, the keys are the heaviest thing on it. Plus when I was driving home today I noticed a kind of grinding sound coming from my vehicle and it would lose a few MPH's but then be fine. I do not know if the problems are connected or what. Please help.