A:My garbage disposal does this sometimes too. Generally its because a residue of food has built up in the trap (u shape pipe) below the disposal. I run lots of very hot water through the pipes for 2-3 mins to get any grease out and run the disposal at the same time. Your dish washer can put food stuff in your pipes also. I am on a septic system so I never use draino or other chemicals...Hope that helps.
