I really sympathise with what you're getting into. My current delimma is in the catch portion of the Snatch. In lifting weights around 1/2 BW and up somewhere around the second and third pull my shoulders just seem to give out when coming down for the catch. In really self-analysing it, my best guess is the need to work on lower body explosiveness, kind of like what Leslie was describing. The other aspect i've noticed trouble in is stablizing my hips during the OHS. After a few reps of light weights my rear lats really start to feel a strain and my iliopsoas seem to get quite a bit of strain as well. Maybe do flexibility work in the hips with a little explosives from snatch work variations?
"Nobody who ever gave his best regretted it."
-George S. Halas