That's a serious problem turning off a computer while it is booting up.
Let's try this:
As the computer is being turned on tab F8 repeatedly.
This will take you to a window where you can select "safe mode"
In this mode not all your drivers
Windows 7 have a repair function. Use it, go to the control panel and there will be a section called system and security. Down at the bottom of that page make sure the check mark is check for troubleshooters. Then let the computer find the error and repair it. Audio has its own section.
2. Go to the run menu and type in msconfig< then go to the start up tab < you will see a list of all the start up items. uncheck most of them ;leaving all microsoft items checked. then try and reboot and see if the computer boots. You can always go back and re-enable them by rechecking them.
Let's start here and I will monitor this thread.