Bad Transmission?

Hey, I'm having problems with my '94 5.0 Mustang. I was driving into work today on the interstate, and due to traffic I had to slow down to about 30mph. Anyway, when the transmission changed gears the car kind of kicked back. It is an automatic transmission. Then, as I proceeded to drive to work this happened once more as I was just driving along, as if the gears slipped in and out or something? Idk. Anyway, I got closer to work and was finally off the interstate. I was driving down this road doing about 20-25mph, and out of no where my car came to a screeching halt. As if I put the gear into park, while driving. I tried to put the car into park, and then back into drive but it wouldn't go anywhere. I then put it back in park, and shut the motor off. Started it back up, put it in drive and was able to make it to work (about a block away). But there is a strange noise coming from underneath the car. I'm not too auto savvy, so idk exactly what the problem would be. So I'm asking what does it sound like to you guys?

Thanks in advanced. I have to leave work and go to class now, but I'll be back in a few hours to post any other info you might need.

-Jon