Shawn is right. Crystallization occurs when the resin gets cold, but it's not spoiled. Warm it up and the crystals will redissolve. But if you just bring it back up to room temp, they will reform. Take it up to 120 F., let it get good and clear, and there won't be any adverse effects on the resin. It's OK to leave the pump in the bottle, but the water trick may not work as well as putting the whole bottle on top of an oil-type space heater on medium-low for a couple hours.

Sometimes granules get trapped in the check valve at the bottom of the pump. If that happens, it will throw the ratio off and that is Very Bad. Check the next few batches with a measuring cup to make sure you're right on. If not, purge the pump with acetone or MEK. It's easy to take the pump apart but a messy proposition, so try first just pumping the solvent through.