I checked the iRobot website and followed their troubleshooting tips. At the end they say something like "If you are still having this problem contact iRobot Customer Support." So I clicked the link, fill out the form and send it into the ether.
20 minutes later I have an e-mail back from them saying "please call us, we need to troubleshoot this over the phone". They also asked that the Roomba be fully charged.
So I charge the beast and then call iRobot. Navigate the phone tree and get to a live human in under 5 minutes. He then looks up my case and proceeds to tell me that a sensor needs to be replaced. My warranty is expired (I knew that) and so my only option would be to buy a new Roomba. They did offer a credit of more than half the price of a new unit. Still it was more money than I wanted to spend at the moment.
Why couldn't the bad sensor be mentioned in the troubleshooting article? Why make me charge the sucker first when it will never be useful again? No additional troubleshooting was done when I called so it's pretty obvious to me that the only purpose of the call was so they had a chance to sell me a replacement. I told the guy that I wasn't interested, that I saw this as a black mark against iRobot and told him good bye.
I guess I'll tinker with it and see if I can convince it do something useful. Or maybe I'll build a turret. Those a round, right?