My Lenovo 3000 reboots while working or after 5 to 10 minutes of non use freezes, screen goes black but power is still on - I do not have hibernation or any automatic turn offs turned on. The screen is black and cannot even power it off but must pull battery - this happens every time. The reboots are intermittent but as soon as I stop working on the computer it freezes. The power light is on and the battery light and the other light (looks like a star lower left) but cannot do anything except pull battery. Have downloaded updates and run virus software to no avail.
It could be a power problem. Did you trying turning off your computer, removing the battery, and connecting it only to AC power. See if the problem continues. If it still does, it could be a software or hardware problem. Did you check power options? The laptop automatically changes power schemes when going on battery power. Go to Control Panel>Power Options>Power Schemes and see if anything is set to turn off in a set amount of time.
When a laptop is not being used for some time it makes some devices to turn off. Your issue seems to be related with HDD. After some time it is stopped, because you do nothing, but then it can't spin up again... I'm not sure, but worth checking. Try finding power managment profiles and disable auto-stop of HDD after time.
Check event viewer maybe you can find solution to the problem. Try to disable all power management. If this doesn’t solved your problem try to use Linux live CD, just to eliminate any hardware problems
I figured out the problem - I am using an HP Laserjet 1100. This printer has a parallel port only so I am using a parallel to usb adapter. HP does not support this running usb. If I leave that printer plugged in my computer goes into some wierd power save mode that will not come back up or reboots itself every 5-10 minutes. I just now have to unplug it when I am not using it and all is fine.