@ the OP - I normally pull the back off and let it sit for about a hour. Then I hit the front on LOW with a hairdryer (just enough to warm it up). Then I let it sit for another hour. Then I put a little silicone grease on the back seal and close her up. So far, it's worked every time. [you can get a cheap set of tools from fleabay]
EDIT: http://www.ebay.com/itm/16pc-Deluxe...947?pt=LH_DefaultDomain_0&hash=item20c7d20f5b
If you love your Rolex(es), get a proper caseback opener. I like this one:
http://www.ebay.com/itm/Oyster-Wate...852?pt=LH_DefaultDomain_0&hash=item20d09b5f34