Sleep light blinks when attempting to turn on MacBook Pro 17", Mac OS X 10.5.8

For the last week or so, when attempting to power on, my MB PRO 17", running Mac OS X 10.5.8, will either boot up to the login screen and after signing in, the SPOD starts up and spins and nothing else happens. A few times it has let me login and actually get to my desktop, but when trying to do ANYTHING, it freezes and the SPOD starts up and spins and spins and spins. I've tried the start up in safe mode and it won't happen; I've tried startup in target disk mode and then restart and nothing, I've tried to start up with the hardware test and nothing. Now, the sleep light just blinks and blinks and blinks after attempting to power on the computer. No I don't have the installation disks anymore, they were lost during my last move, so reinstallation is off the table. That's pretty much it, anyone seen, heard or dealt with anything like this before?