Off AC goes to sleep, can't wake.

If my MacBook is taken off the charger and is turned on, the battery runs down and goes to sleep; like it should. When I try to turn it on again, it won't come out of sleep mode.

I can push and hold the power button until it turns off and when I press it again, I hear the typical CD drive check and if I put me ear to the wrist rest, I can hear the HD spin up, but not read.

I have tried the various resets for PRAM, PMU, remove the battery/AC hold power button, reseat the RAM, etc. and nothing seems to be working. I had this same problem a month or so ago and I was able to somehow resurrect it. I told my wife to always make sure and leave it plugged in if it is on so we avoid the problem, she forgot that it was on last night and here we are today.

Update: I ordered a PRAM battery off eBay that supposedly is good. I put it into my MB and nothing has changed. I did find however that when I push and hold the power button that the sleep mode indicator has an unusual flash pattern. Does anyone know where I can look up flash patterns and what they mean?

Anyone have any suggestions as to what my problem may be?