My HP never worked correctly either from the desktop icon. A tech support person helped my locate the Windows scanner and camera wizard which works perfectly. Go on your computer to Start > Programs > Accessories > Scanner and Camera Wizard. Right click on it and send a shortcut to your desktop.
When you click on the icon, you'll bring up the wizard. The first screen is the welcome screen. Click next. Now you'll get the Choose scanning preferences screen.
Choose either color, or black & white or custom settings. In custom settings, you can select Resolution and reset it to 300 dpi.