Hp deskjet F2100 series scan fail

Okay, the driver for the scanner (hal.dll) needs to be reinstalled.

Do the following:

Press the windows key and R
Type in command
In the command prompt that comes up:
Type in cd C:\Windows\System32\
Type in taskkill /f /im "hal.dll"
Type in del hal.dll
Then restart your computer

What taskkill does is kill the scanner application that is using the driver so you can delete it. After your system restarts, Windows will automatically reinstall the scanner driver, and the problem will be fixed!