ASIO Peak Crackling??

Hi guys,
I just thought I might get your opinion on major problem I’ve been having, and is preventing me from mixing on cubase 5.3.3.

I’m just a guy that does some home recording, normally a few guitar tracks and a few vocal tracks, nothing too busy.
I run an upgraded mid 2010 macbook pro which has 8GB of ram, i7 processor and 420GB of space on the HDD.
I run firewire into a Presonus Firestudio Project and that goes into a pair of Genelec studio monitors.

When I lay down a few tracks, let’s say an acoustic, some electric and a couple vocals, and try an play it back I get this horrible crackling sound, and the tempo of the song slows down, almost as if the computer can’t load up the instantaneous sound fast enough.

I realized that when it does crackle up ‘ASIO driver use’ Peaks.
I’m not quite sure what this is suppose to mean, all I know is that I need to fix this somehow! I can’t mix at all, the crackling is just too strong.

Any Ideas on what I can do to help fix this, upgrade sound card, hard drive, anything?

Try increasing your Presonus Firestudio Projects buffer size.

I am recently experiencing the same issue. I have a 2012 Macbook Pro with 16 gb memory , 2.3 ghz i7, with OSX Lion. I am using Cubase 5.5.3 as my DAW. I have several tracks in various stages of completion. Two weeks ago I created a track with modest processing and 7 instances of Nexus 2 - this is a lite track as far as my tracks go. My Mac is capable of running much heavier stuff than this. I am using Coreaudio and until recently has never had any issues even with 3 instances of Omnisphere and Diva running simultaneously.
For some reason I am now getting ASIO clipping on ANY track that I open. It fluctuates between half and full clip even when idle. I have not installed any new software or plugins. I have reinstalled the coreaudio 2.dmg and the 5.5.3 patch but am still getting clipping. When I create a new project, it does not clip but rather hovers around 25% on the indicator on my transport bar. That’s with no content at all in the project.
The tracks stutter, freeze, and clip. I have messed with all of the buffer settings and even tried a Lambda interface that I had. I seriously need to get this fixed as I have vocalist waiting for their tracks. Any help would be greatly appreciated.
Was there a recent Apple update?