One thing you could try from the account which will boot is to Start > Run > msconfig

On the general tab, click the 'Selective Startup' radial, then uncheck the 'Load Startup items'. If you then go to the Startup tab, you will see all your startup items have been unchecked. Once you click OK, you can restart your PC which will restart without all your startup programs. If your CPU remains normal, you will then need to select each startup program one-by-one until such time that you find the culprit.

When you restart, you will get a warning that you are in selective startup mode - this is to be expected. If you ever get to a point that you are happy, you can check the box to tell Windows not to warn you again.