Sometimes, deleting the "HPCD.sys" using the software "FreeCommander" works. For more details you can refer to the below mentioned link:
As you mentioned there are thousands of Registry errors and Virus infections on the computer, if you make a Recovery Disc for this Operating System, next time you install your Operating System using these discs those errors will still be present. Another fresh installation of Windows on your computer is recommended.
Kindly get back if there are any further queries.