Just installed Windows 8 Pro - LOVE it, most everything works great. However, sometimes when I unplug my laptop it restarts, and I don't mean it shuts down and reboots - it jumps to my HP startup menu screen and proceeds to boot from there. All programs closed out and everything; not hibernating. It makes it a real pain to charge my laptop. There's no problem with my battery - ran a load test and it checked out just fine. Any ideas what might be causing it?

Windows 8 Pro
HP Elitebook 8540w
i5 vPro 2.67 ghz