I can print with my HP printer/scanner/fax, but only SimpleScan allows me to scan pages. XSane dependencies are all met, so is HPLIP, but all I can scan is a single white line against black background.

The original thread is this one
http://ubuntuforums.org/showthread.php?t=1895376
, but with a not so informative title.

Note to admins: I have been trying to rename the title of the linked thread, but I cannot. I feel this title informs better about my problem.