Assuming a gradual enough of a stop so that you don't crash and burn along with most other stuff on the surface, different things will occur depending on whether you are in daylight or at night. The day will become the length of a year. While you are in the sun the van will bake, the balloons will pop, and you will cook like a well done roast. Meanwhile the helium will rise to the top of the atmosphere and some will escape into space. When night falls you will then freeze like the leftover roast in the deep freezer.
If you are stopped at night the balloons will slowly lose the helium since it will escape out the small holes in the rubber, but since it will get cold, the rubber will become brittle as well, so they might pop even with lower pressure.
There will be a slight increase in felt gravity since the angular acceleration that tends to throw you away from the surface will be gone.
If along with the loss of rotation about its axis, the Earth were to stop its orbit around the sun, well you wouldn't have to worry about freezing to death if it were night when it stopped for you.