HAL is short for Hardware Abstraction Layer. It contains programming for the Windows operating system to function as an interface between your hardware and software. Applications don't access hardware directly, they access HAL, which then passes on the information to the hardware. HAL allow applications to be device-independent.
If you're having problems with HAL, you will need to boot from the recovery disk that came with your computer. If you don't have one, contact the manufacturer and they will sell you one for a small fee.
With the recovery you can reinstall your operating system without losing any data. You also have the option to format your harddrive completely before the operating system is reinstalled— it would cause all data to be lost, but would give you a fresh start.
It's common for HAL to become corrupted because of a virus or malware. If you suspect that a virus or malware caused this problem, a fresh start would be the better choice to reduce the chance of becoming reinfected.