Gateway Laptop power settings don't work

[SteveMP170]

I am using a Gateway laptop running Vista (64bit). I have had it for almost three years. It was tough enough going from Windows XP to Vista, but I notice that my power options are not working as programmed. I have the computer set to turn off display in one hour and go to sleep in two hours while plugged in. My problem is that this thing shuts down early---always, and I never know when it will do this!! There doesn't seem to be a sleep mode that I remember from earlier systems, so I can never just move my mouse and gain access without rebooting the computer all over again. I don't like Vista anyway especially where things I've used and become quite accustomed to for twelve years of Windows XP are now not available on this OS. Could someone tell me what is going on?

This system has a Pentium dual core processor T4200, 2/Ghz, 4GB memory, 320 Gig HD and 64bit OS.

[Train]

Have you calibrated the battery lately? Do not know if that would effect it while plugged in though.

http://h20239.www2.hp.com/techcenter...attery_max.htm

Yes, HP got somethiung right. Even works on my Toshiba.