Illustrator CS 5.5 has memory issues when I create "distressed" looking art.

Question

I work in a screen printing company and we often get requests for art work with a "distressed" look. I usually creat the art work and fake a distressed look with a grunge brush that I expand and unite with the pathfinder tool. I then color it to the substrate color, or white for creating seperations. The "negative space" becomes individual paths that cause lagging on my computer. 
We recently upgraded to a computer w/ 64bit processor w/ 8 GB of Ram (though even on the old computer, we had the same issue).
My issue lies in that when I create multiple versions of this art. I get a warning about lack of available memory (which we should have plenty, as this when I save the files it takes significantly longer than other artwork).  I have adjusted the scratch disk settings to work of an external drive.  But when I make too many copies (which I have to do for the sepperation process) a warning window shows up that says:
"Can't Finish previewing. Could not repeat the requested operation."
and it switches to a wireframe preview.  Then if I try to save, it says "An unknown error has occured."
I've attached images to illustrate this problem.  I had to do quite a few more copies of the art to illustrate the point, but significant resources are lost and I am usually unable to save my work when this happens.  I often have to do color seperations, so this requires multiple versions of the same art.  I've lost many hours on this "bug".
Is there any tips, resources or anything available that you can let me know so this stops happening.  Distressed logos are in style, and I can't tell my employers that I can't do them when they bought a new computer to handle the limitaions of the old one.  This same thing has happend on both the old computer and the new one.
How art looks on mock up
"Distressed" part of art selected
wire frame
Error message

Answer 1

Distressed logos are in style, and I can't tell my employers that I can't do them...
You're workflow is the problem. You are trying to use a vector program to emulate raster-based results, and trying to solve the resulting problem by brute force (throwing additional hardware resources at it).
There are several very widespread misconceptions associated with this commonplace scenario, stemming from confusion between the concepts of vector-based artwork versus raster-based artwork--as opposed to line art versus continuous-tone artwork.
Silkscreen printing does not necessarily require vector-based artwork. It does, however, often require line art. But line art can be vector-based, raster-based, or a combination of the two.
Mathematically-defined shapes and algorithmically-derived interpolation (blends, grads, etc.) are the purview of vector graphics. Granular detail and texture are the purview of raster-based imaging.
There is no reason for you to insist on using a kazillion individual tiny, irregularly-shaped vector paths combined into a huge compound path in order to simulate a so-called "distressed" texture. Just use a 1-bit or 8-bit (with alpha transparency channel) raster image for the texture. Color it white and position it in front of the vector-based elements and print your separations.
Alternatively, take your vector-based content to your raster imaging program, rasterize/separate it to appropriate spot color channels and apply your textures there.
You'll find that you don't need additional hardware resources and that you have much more texture versatility.
JET