That I don't mind, shtick actors/comedians breaking out of their shtick roles; one of my favorite movies of all time is Coming to America, an Eddie Murphy movie where he's not being his usual wise cracking self. Jim Carrey definitely did a good job in KA 2 as did Nicholas Cage in the first one, both, I feel, normally have a shtick and both managed to not fall back on using their shtick in their roles which really helped me believe them as their characters and not just Kim Carrey or Nick Cage being their normal movie selves again.
There have been alot of comedic actors that have broken out of their molds. Tom Hanks (eg: Bachelor Party) started on a show called Bosum Buddies... Bill Murray has gone from movies like Stripes and Ghostbusters to serious roles... Jim Carrey... Rob Schnieder,.. Robin Williams... Danny DeVito... Will Smith... the list goes on. The problem is that we love them best for their comedic roles. I know I prefer seeing Robin in a Comedy role over his more serious work (not that his serious work was bad) its just that I think he feels more comfortable making people laugh. But I can understand how the same type of humor shtick can get tiring when the actor involved isn't that funny to begin with. A few that come to mind are Tyler Perry, Pee Wee Herman or the Ernest movies. I thought PeeWee did a great job in Mystery Men... it was outside of his comfort range and really made him stand out as an actor. What I hate thou, is when they take one hit wonders and try to build movies around them that tend to fail miserably... lets take a look at Toby McGuire and Shea LeBeouf, Neither are very good actors but they do one movie that was really good and they feel as if they have to put them in anything to bring more money to the box office.