This sort of problem is usually linked to the driver. See if HP has a more recent driver and install it. Make sure you uninstall any previous versions.
When you are ready to install it, unplug the scanner from the PC. Install the driver. Switch off the PC. Connect the scanner. Start up the PC. Windows will detect the scanner and load the drivers.
Within your OCR software make sure that you have the scanner selected, usually in the Tools Menu...