Did you try and do a recovery when you reinstalled it?
When you start the pc up keep your finger on F8. press the key on your keyboard, turn the pc on then after a few seconds you will be presented with many options. Select the run operating system at last known good configuration.
Also if you can try to boot up into dos and then type without speech marks
there is a space between the g and the /
then select the oldest of the five options presented to you.
if it doesnt work please post back