I have a 2007 Race Face Evolve SS Crank on my Surly Karate Monkey. When I am riding every day, about once a week, the drive side (which has the splined side) works its way lose so the drive side starts to wobble. As soon as this starts to happen, I get off and walk. Nothing appears to be rounded off/damaged/etc, but it just doesn't seem to want to stay tight. I am about ready to bust out some locktight, but I thougth I would check here first and see
1. If this is a common issue
2. If this is something I did wrong when installing (I did it at my lbs with help from the mechanic, so it is not like I did it in my garage with a six pack some night). I did have to use one of the plastic spacer rings that came with the crank in order to acheive the correct chainline.

I really don't want to ruin this crank (if it is not dead already), so help would be greatly appreciated.

One more thing - I have never done anything remotely rough with this bike. Promise. I am actually somewhat ashamed of how soft I have been with this bike, but until this issue is resolved, I will continue to play it easy.