7.5 on Ubuntu 9 Jaunty .....sound pops and loses sync

I installed 7.5 for ubuntu jaunty and the install seemed to go well.

When I put an avi. into the editor and play it back it has popping or crackling sounds which are not in the original file. It also looses sync.

Any advice? I would sure love to use this program so I can ditch Windoze for good.

Yeah I am new, I admit it.