MacBook asks if I want to shut down when inactive for ONE minute!

My early 2009 MacBook 2.0 ghz asks if I want to shut down when inactive for about one minute. Won't sleep (shuts down instead). I did all the SMC/PRAM/DiscUtility stuff. Swapped hard drives and logic boards. Same results using Leopard or Lion. Bad Ram? That's the only thing I haven't swapped out or replaced yet! Any help would be greatly appreciated as my next step will likely be an "as is" sale on eBay.