Comment 41 for bug 181242

I have had the same problem with a hp1020 laser jet printer the problem was with hardy kubuntu 8.04 the problem was that the hplip setup detected the printer installed it but then the printer can't be probed and the firmware can't be loaded this was due to the following
root account is disabled (locked) in ubuntu and if u take a closer look to the udev rules for hp you will see that it's all owned by root also the device lp0 in both /dev/usb/lp0 and /dev/lp0 are both owned by root (Try ls -l /dev/lp0)
so this wouldn't have happened with bsd however it happens here with Ubuntu there are actually two solutions for this the first is

to change the 55-phmud.rules as david did here for he changed all the users to own part in the rules to user lp (make sure you have user lp :) ) but the trick here is to put the file in the installation dir (udev dir) and then reinstall after that it should work just fine

the second solution is

just go to user management unlock root then add all privileges to root to access all open a terminal and su to root when u login each time and the printer should work just fine with the original install

This is just a temp solution i recommend anybody here in touch with HP LIP to talk to them about modifying the 55 files in the rules to suit all (meaning no root privileges)