Run the Boot Startup Repair... you can run it from the Windows installation Disk, or sometimes it can be run from the Safe Mode Options... If you don't have the Windows DVD Disk, Start the computer and press F8 immediately after the Bios beep, and hold the F8 key... the option to run a Startup Repair should appear on the screen, follow the instructions and wait for it to complete before restarting the computer.
If the Startup Repair doesn't help your options are:
1. you can remove the hard drive and connect it to another computer via USB adapter.
2. Scan the Hard Drive with Hard Disk Sentinel to know it's condition.
3. Scan it with an antivirus and/or antimalware. If bugs are found it may now run in the laptop...
4. If scanns don't help,
5. You can also use a Live CD: a Windows CD or DVD, Hiren's Boot CD, or any Live CD Antivirus to test the computer...
If it boots to the live CD/DVD with normal speed, the cause may be the Hard drive and no other computer component, meaning that you can
a) format the Hard Drive and intall a fresh copy of Windows,
b) or you can replace the Hard Drive.
c) Take it to a technician