I know that at times like this time seem to be of the essence, but you have to realize that we are volunteers here and are helping other members as well. I started responding to topics I'm involved in at 6:30 this morning, I just got to the topic you posted, it has been a usual morning here, busy.
Does the computer finish starting?
If not, try starting again and see if you can write down the error message and post it back here. This will provide us with something to work with.
After you get the error message copied try booting into Safe Mode.
To boot into Safe Mode press the power button and immediately start tapping the F8 key. Eventually you will see the Advance Boot Options page, it will look like the image below.
You will need to use the up or down key to navigate to Safe Mode, once the pointer is on Safe Mode press the Enter key.
Edit: Please note that the area which is highlighted in gray does not mean that this is the Safe Mode you want, it is just what was in the picture. You want Safe Mode.
Edited by dc3, 24 August 2013 - 11:14 AM.