Whenever I render a movie with Premiere anything that is relatively loud goes all crackly. It doesn't do it with any other software, and is not like that when played from the source clip.
Anyone got any ideas as to how to fix it?

Sounds like you need to master your audio big fella. . .

Are you using Premiere Pro? If so you need to go to windows -> layout -> audio (or something along those lines) watch your levels, if they go into the red, it's going to crackle when you export.

For some reason though, it sounds normal when you play it in Premiere. So make sure you chang the volume of your audio tracks, or master volume when there are loud bits.

Hope this helped.

Yes, it did cheers, although I worked it out before you posted

But yeah, it just seemed strange how the audio that the camera recorded was what crackled, when it was the music I was putting over it that was in the red.