Laptop not powering up

I have an IBM Thnk Pad A22M that when powered down, does not start up again until I reseat the hard drive, unplug the power cord and hit a series of buttons. (Not even really sure what buttons) Any ideas what would cause this to happen?

I can shut the laptop lid, unplug the power and reopen the lid and everything comes back. The problem is if I shut down properly. It won't start up again.

I don't have a user manual for this, so I'm not really sure what some of the keys do. I have shut down all power mangement and hibernation mode. The IBM website has a troubleshooting guide, but not a user manual. Does anybody know where I can find a user manual for this laptop?