That's funny, I've just written a chip8/schip emu too, also based on Dave Winter's docs. But just in plain old C. All games are working great, so if you've got specific emulation core related problems, feel free to ask.
Say, could you provide a download link of Tapeworm and Chip8-logo and perhaps others that are not included with Dave Winter's emulator ? Because those are all I can find. Not to play the games, I hate most of those games actually, but to look for bugs and get perfect emulation.
(note to mod: chip8 roms are pd)