Alright so.

Everytime I get more than like, 3 notes going at the same time, even if it's three different instruments on three different patterns, when FL plays it there is a WHOLE BUNCH of fuzzy, buzzy, white-noise pops and stuff!
You know, the sound you get when you turn the amp to 10 and thrash away.
I can hardly hear the music.

Does anyone know why this is?

Sounds like the latency?  Or you sound card is crapping out?