Anybody ever notice how whenever an actor known for comedy does a drama, the movie has the kind of plot that would work very well for comedy? I wonder if this might be to trick the audience into thinking it's a comedy (even though they make a big deal out of comedians doing drama).
I'll use Jim Carrey's dramas as an example. The Truman Show is about a guy whose unaware that his whole life is a TV show, The Majestic is about a man who gets amnesia (and was a blacklisted screenwriter), and The Number 23 is about a man obsessed with the number 23... Those all sound like comedy plots.
I also find it ironic how Tom Hanks was previously known for comedy but later on became better known for drama, with one dramatic example being Forrest Gump. I thought that was a comedy, it has many funny scenes, it was the first Tom Hanks film I saw, and if it is more dramatic then it's ironic how the first film I saw with a former comedy actor was more drama than comedy while I thought it was a comedy (I know, that last sentence is confusing).
And on the topic of movies with comedy-sounding premises, I'd like to point out that the plot of Meet Joe Black (Death spends time as a mortal in society) sounds like a comedy, though the main actors aren't known for comedy.