nicole, turn it over and look for something caught in the wheels. Test wheels by pushing them in and out and making sure they rotate freely. Of course, if you have already tried that and it did not give you any results, then you need to try to run the self diagnostics. Here is link link to a really good site that will show you how to run diagnostics on your Roomba. It should help you to narrow your error down. Also check this link for more info (you are not alone with that problem:-) download the service manual from here. Make sure you save it, apparently iRobot does not like us to look at their manuals :-) Good Luck