Start the computer. The computer begins processing a set of instructions known as the Basic Input/Output System (BIOS). What is displayed depends on the BIOS manufacturer. Some computers display a progress bar that refers to the word BIOS, while others may not display any indication that this process is happening.
As soon as the BIOS has finished loading, begin tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears.
NOTE: If you begin tapping the F8 key too soon, some computers will generate a "keyboard error" message. Please restart and try again.
Using the arrow keys on the keyboard, scroll to and select create boot log.
Then Start Normally...after the boot fails follow the advice above and choose Safe Mode Have a look at th bootlog.txt file on the C drive the final entries are nomally the fail. If so try going into Services and disable whatever is causing the problem...and/or any services you dont need. click here