Collisions going inside one another

I have observed a curious phenominom, when two objects are colliding they sometimes go within each other, resulting in them being stuck.

i use a frame rate of 60 frames per second in my physics frame listener and it happens, i up that to 180 times a second, and it doesnt happen, but surely, with 60 updates a second, no matter how fast objects go, they shoulld be able to pass into one another within 1/60th of a second ?

I am using cyclinders, and it is cylinders that collide.

Another question i have, is that i the scale for the universe is 1 unit = 1meter when using the stardard force callback (gravity 9.. When i create small items, about 2 cm in size, things tend to go through one another even more.

Are there any things i can do to correct this ? is there another way ?

i figured out the whole scaling thing now. Seems it doesnt like things being that small so i scaled the whole world up.

Im still having cyclinders that hit each other side on passing into one another and getting stuck, they also sometimes go through mesh's (tree collisions).

Any help would be appreiciated... is there anything i can do to prevent things from going through one another ? am i forgetting anything ?