Hmm, the most likely thing be would be an error while loading a character or stage in that case, I think. Does the same set of files work when using them with the Windows version? Could you maybe share your files so I could take a look too what is crashing?
Alternatively, is there an error message in the browser's developer console (turned on with CTRL+Shift+J on Chrome and Firefox)? Sometimes it only says unhelpful stuff like "Out of bounds memory access", but occasionally, it also gives an error message which file it could not load or something, that could help tracking down what is going wrong.