My dad has owned the same rice cooker for years and it always worked fine. Recently, every time he makes rice, which is all it has ever been used for, he gets sick to his stomach almost immediately after eating it. No amount of cleaning and rinsing to make sure all soap is out of it makes any difference. It also doesn't matter what brand of rice, even the same ones we have always used. What is the problem? The unit seems to work just fine.
The big question is: what changed? Some possibilities:
The rice cooker isn't being cleaned properly. Doesn't seem likely that the residue on an even poorly-cleaned metal pan would significantly contaminate the results.
The water or other cooking ingredients. Doesn't seem likely since the water is probably the same stuff you drink, and generally there aren't any other ingredients when using a rice cooker.
Your dad. Has he developed some sort of allergy or reaction to the rice?