Actually I'm having the same exact problem. My Mid-2009 MacBook Pro 13.3 inch goes to sleep permanently after closing the lid. I will open the lid up and the light is still pulsing, but when I click the power button nothing happens. I have to hold the Power button until he machine has turned off, then click it again, sometimes for some odd reason it will continue with resume, or it will re-boot. I have already reset the SMC, and PRAM. No luck at all. Once the lid is closed you can't have it recover from sleep mode by pressing a key or clicking the trackpad.