After a brief chat about general topics such as the fact that Rosencrantz and Guildenstern are down on their luck a little and that Hamlet feels Denmark is something of an emotional prison for him right now, Hamlet asks his two old friends why they are in Denmark. Rosencrantz gives a hurried response that they are there just to visit him and nothing more.  Hamlet suspects they were sent for and asks them that directly.  Since R and G aren't good at lying, they quickly confess that they were sent for.  Hamlet says he knows they were sent for to try to determine why he has been acting so depressed and mad lately.  He also tells them that he's only crazy sometimes; other times he knows what is going on. R and G fail to take the opportunity to explore further what Hamlet means by this remark.  In Act 3, sc. 2, after the interrupted play, R and G again try to talk to Hamlet, but they make the mistake of telling him, right off, that he's upset the king.  Since Hamlet's goal with the play was to see if the king would become upset, he is not displeased with the news that Claudius is angry.  On the contrary, this proves that the ghost told Hamlet the truth about what happened.  By aligning themselves with the king, R and G have turned from "friends" to "enemies" in Hamlet's opinion.  That turn ruins any chance they might have had in finding the source of Hamlet's madness.  Neither one of them is smart enough to get information from Hamlet and their attempts are weak.