This should be in the Production forum, not DJ forum. When/if you ask there, be sure to include more info about your setup (primarily soundcard) to help people help you.

Kiragan

yea, this belongs in the production area.. but the answer to your problem is your soundcard... if you are haveing cracks or pops its usually your soundcard that is at fault. try upgrading .... even upgradeing to a soundblaster 5.1 card should give you much better sound quality and def. no cracking or popping. if you already have a SB5.1 or better then i dont know what else to say.

Yes, while sound card might be a factor...more than likely it is your CPU.
When you have an entire song going in FL with 10+ synths loaded, it is a huge CPU drain. On my computer, I can't even playback some of the songs I have made in the program, I have to export them first.
Try disabling individual channel monitors and the monitors at the top, those are crazy CPU drains (as I found out from my friend).

The cpu is the reason you are getting those cracks and pops. YOu might try disabling the FX when you play it back to save some cpu power if it gets too bad. Otherwise you may have to export it to mp3 every time you want to listen to it.