Likely your hard drive is bad, at least a few sectors from what I have read.
The most likely method I think to get it to work (requires a second computer) is to remove HDD from laptop, connect to other computer, run checkdisk on the HDD which will most likely show an error and fix (or exclude) any bad sectors. Defrag HDD, reinstall in laptop.
Another option I read (with less good results) is to start laptop and repeatedly tap F8 key to bring up a load last good configuration option and try from there.
Hopefully you can get it going using the second computer method. I've read that an alike OS is best for that but I don't think it's a requirement (not sure).