Have a brand new compaq 2175US laptop running Xp Pro. All attempts to restart fail. Shutting down and powering back up works fine. Selecting restart or restarts caused by updating or loading software fail to restart. The computer shuts down, the power light goes off and comes back on as if it wants to restart but nothing happens. I have to hold down the power button for the usual few seconds to shut it off and then power it back up. Any thoughts?