] She never seems to suss out that Claudius is guilty until she is poisoned. Was she just in denial or did she truly think Hamlet mad and that what he said was just "the very coinage of [his] brain"?

This is hard, isn't it?

Of course, it's to her advantage to believe that Hamlet is mad. In her mind, the only offense she is guilty of is (*snort* - yeah, only) a hasty marriage to her husband's brother.

So - assuming that's not enough.....Hamlet has now hit her with the reality (or is it just his madness?) that she has married her husband's murderer.

Perhaps it's both - we can easily convince ourselves to believe what we want to believe. Hamlet's madness - however distressing - is nothing in comparison to Claudius's guilt.

The real difficulty lies in the fact that Hamlet has asked her to perpetuate the idea that he is mad. So......is she merely keeping her word to her son, or is she speaking what she truly believes? However misguided and weak G may be, she does appear a loving and concerned mother. Meanwhile, Hamlet's discourse with a ghost she cannot see (and whose prior appearances she knows nothing of) would give her good cause to believe that Hamlet is mad. Meanwhile, I would imagine that Claudius has been all that is charming and loving to her - giving her no cause to believe him capable of what her son accuses.