Is there any risk of illness from eating a chicken dinner?

Yes, particularly if it wasn’t thoroughly cooked or was  improperly handled prior to cooking. Recent studies indicate that up to 83% of fresh, whole broilers may harbor campylobacter or salmonella, either of which can cause the consumer gastrointestinal distress. As a result, most cases of food poisoning are caused by contaminated chicken.  Although poultry processors must adhere to food-safety protocols to ensure that their packaged products are pathogen-free, salmonella has proved an especially tough nut to crack.
 
To prevent illness, consumers must cook chicken to an internal temperature of 165° F. Proper product handling is also a must to prevent cross-contamination on counter tops, plates, utensils, and other items.
 
Additionally, chicken may be subject to spoilage if not stored at a temperature of 40°F or less or if stored at a proper temperature for an extended period. Spoilage bacteria generally aren't harmful but eventually may alter the taste, texture, and/or appearance of the chicken.  Fortunately, proper storage  and cooking prevent most causes of illness. 
 
Sources:
ConsumerReports.org "Dirty Birds"
 
Consumer Reports on Health, September 2009.