94 3000ex transmisson problem! help!

I was drivin my 94 300ex stock motor piston and everything. It has just been rebuilt maybe 4 hours. I was driving and it made a screetchin noise so i killed the motor and locked the breakes in. When i went to get back on it it acted like it was in gear. The back tires wont move and when you put it in neutral it jumps in gear when you try to start it. It will switch gears but not move. And when you go to first and try to move and release the clutch it tries to move then doesnt and it dies.