PLEASE HELP with cracking/popping noises in recording and playback - at end of my rope :(

We have gone through the recommended adjustment to eliminate "latency" and cracking and popping noises that appear when we record and playback. 
 
Using the unit LIVE, it works like a charm.  Using it for record however, is very disheartening because we record and get a good take, and then it's ruined by these cracking and popping.  I've contacted the tech department and they sent an email with recommendations.  We've done all of the adjustments.
 
Has anyone else had trouble with this and found a way to eliminate it?  I'm running the program on a laptop that meets requirements.  It's running with Windows XP. 
 
I just don't know what to do.  Ive spent alot of money on this stuff.
 
 

It's an older Toshiba Satellite that had a lot of crap loaded on it. I've removed everything I could find with still leaving basic functionality (I really don't want to get rid of the CD drive or the ability to burn a disc). I shut down all the network stuff, opened a latency monitor program that tech support recommended, and then started shutting down audio drivers. I shut down something called the Real Tek HD audio driver and the latency on the monitor went nuts. So I backtracked and stopped shutting things down.
 
I've monitored the latency program while recording and everything seems to be fine except every now and then latency spikes real momentarily and that produces a dropout in the track. It doesn't seem to track anything I'm doing (I've tried overloading everything I can think of). It doesn't seem to have any correspondence to the CPU load or anything else. When I shut down the laptop, I get some kind of hang up where Exploer won't shut down properly. I suspect there's some kind of IE remnant glitch that's driving the machine crazy. I'm almost tempted to wipe the hard drive clean and start over, but I'm not much of a computer geek and probably could never get the dang thing back.
 
I have no real idea what I'm doing and appreciate any stupidly specific suggestions (believe me, I'm not afraid of my ignorance).
 
Thanks for whatever you can suggest. 

I found the restore disc that came with the computer and just wiped the whole thing clean and reinstalled the Sonar software. I took all your suggestions (they had also come from tech support) and set everything up. I figured that it was easier to start over from the basic and add back in the things I want rather than chase things I don't want that may have been left there by something added a while ago.

So far the the system seems to be working. Tomorrow we'll try recording a new project and stretch the whole thing out.

Thanks for the help so far. I'll let you know what I find.