Killing My Meats

I'm a fan of cooking, partly because I like to eat, and because it's relaxing for me. I've grown accustomed to using a stove and an oven, but felt like expanding my repertoire. A little while ago, I bought a slow cooker in hopes of venturing into the land of tender eats and all day cooking. People say that it's nearly impossible to ruin food in a slow cooker, but apparently I am the exception to the stupid rule. I can make soups and pasta sauce in there with no problem, but when I start putting in meats, they come out tasting like crap. It smells amazing, but insanely dry. In fact, I tried making a beef roast in the slow cooker today, and when it was done, I took one bite and for the life of me couldn't swallow it because it was so dry. I honestly felt like I was chewing tree bark covered in sand. I have no idea what I'm doing wrong, but I think I might retire this slow cooker and go back to what I know best, the good 'ol stove, oven and microwave.