You are having a friction issue. That could include a few things. This is what I would check:
Check the wear of your walking belt (the belt you walk on). Loosen the belt and stick you hand underneath it palm up, run it from left to right. You are feeling for 2 things. First, does the underneath side of the belt feel smooth or textured. If it's smooth, replace your walking belt because is it worn. It should feel like a screen door or a canvas. Second, your hand should feel greasy. If the belt is textured, but just dry call the manufacturer and get the lubrication. I wouldn't use silicone.
If your belt is textured and has lubrication, tighten your walking belt. If you're still having the same problem, take off your motorhood and check your drive belt.
Good Luck!
NordicGirl, July 2009