|Have you flashed the bios since that last worked properly?|
If you have, flashing the bios usually doesn't load the cmos contents for the bios version you flashed with, so if the bios version you flashed with is different than it was previously, the cmos contents don't match the bios version. Go into the bios Setup and load bios defaults, or better still, optimal bios defaults if that's listed, save settings.
Have you reloaded Windows from scratch since the last time that worked correctly?
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, USB 2.0 if it has it, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.
That is especially important for lapop main chipsets.
Laptop keyboards are not as durable as desktop keyboards, and they are more likely to malfunction.
Have you tried an external keyboard?