Tile Collision Material

I'm playing around with a little platform game and using a constant polar force to simulate gravity. The player collides with tiles nicely but I cant seem to get a constant movement going while standing on top of the tiles... it seems the gravity forced collision is sapping both horz velocity as well as vertical.

Do I need to modify the tile collision material (it currently has friction of 0...)?

HELP! My little man can't run! ;) Thanks