If you mean the Language Bar button under Preferences, it's not available unless one of the following is installed and added as a text service: Speech or handwriting recognition or an Input Method Editor (IME)
In Regional and Language options --> Languages tab --> Details button --> Advanced tab, under the system configuration section is "Turn off advanced text services" checked?
Sounds like the new power supply is busted. Does the power supply have one of those on/off switches on the back of it? Did you check that? (I know it's a stupid question, but I gotta ask it)
Either it's just another windows annoyance, or someone, somewhere is using your username & password. Unless, you use msn messenger somewhere other than your home computer.
I tried the auto reboot thing once, but I put it in the wrong place and my computer rebooted before everything was installed, so I just took it out. Check out the unattended guide, it should help you.