A lot of movie sites out there are calling Wesley Snipes crazy over his $5 million lawsuit against New Line Cinema, but I disagree. Of course it's not clear cut, especially considering the fact that he may be having financial difficulties (he has a Florida home close to foreclosure due to non-payment of taxes, and he lost another one for the same reason a couple of years ago). Personally I don't understand how people can get paid millions of dollars and then end up broke, but that's just me. In any case, this certainly casts doubt on his motivation for filing the suit.
However... this did not come out of the blue. Way back at the wrap of production of Blade III Snipes sent a five page letter to the head of New Line complaining about the choice of David Goyer as director (of which he was informed six weeks before shooting), his treatment on the set and general misgivings about the film.
In the lawsuit Snipes elaborates on the (racial) mistreatment as well as stating that he is still owed a couple of million dollars and wants damages in addition to that. He complains about the juvenile humor in script (I certainly agree with that) and the fact that the film seemed to be more of an attempt to spin off a new series based on the newly introduced characters than a Blade film (again, I have to agree, see my review of Blade III).
I certainly don't know what went on during production, but apparently it was enough to prompt Snipes (and yes, I realize that even "tough guy" actors can be primadonnas) to write a lengthy letter of complaint. Seeing as (IMHO) the movie does indeed suffer from everything he mentioned in his diatribe and lawsuit, maybe he's not as crazy as some other sites are suggesting.
In any case, you can probably forget about ever seeing Blade IV.