Sorry, there isnt a magical way to get it off.
All i can say is that when cold thermal paste can get REALLY hard. so i would turn on ur system for about 15min then turn it off and try to get the cooler off immidiatly.
Yeah I was going to suggest this as well. I'm not really sure why there was a big influx of useless and offensive posts, but I'd go with this idea.
I think there was another guy with a problem similar to this, where he stuck it in the oven for a tiny bit and managed to get it off, but since your comp is still functioning, just turning it on should be fine.