There are certain chemicals in wood smoke that cause meats to retain their pink color. If the meat is tender and its temperature is over 160 degrees, it's done and ok to eat. The pink color, called the smokering, is a desirable characteristic of smoked meats.
Now, if the meat isn't done, that's means that your smoker isn't getting hot enough. For ribs, the smoker temp should be at least 225 degrees, but not much more than 250. If the ribs are still uncooked after 5 hours, do what's necessary to increase the cooking temperature of the smoker.
