thrilled...... It sounds like it could be one of 2 things to me..... First and easiest is that the shifter linkage could need to be adjusted. Second and more serious is it could have a bent shifting fork (transmission internal problem). If the fork is the problem it would have to be replaced.

By the way.... The problem you have described is called "popping out of gear" Not "shifting it's self" into neutral.

How many miles do you have???