Ok I just had a quick looksee and I saw that you had wait(1) in wrong places.

Also wait(1) is supposed to before c_setminmax(my) not after.

Try adding the wait(1) at the end of the process, unless you ment
for them to be that way.

eg:
while(1)
{
do some stuff here
wait(1)
}

Hope this helps..
There is a physics demo getting around, on acknex resource site.
Also have a quick look in the physics forum, some good tips in there
as well.

Good luck..