Situation: Clean install of 12.04 and of HPLIP 3.12.4. The printer is detected and installed correctly. The problem starts afterwards.
Whenever entering the session, HPLIP starts and is shown on the menu bar (in 11.10, HPLIP didn't show until the printer was plugged in). When plugging in the printer, HPLIP gives a 'Devise communication error', and won't print.
Workaround: After much fooling around, I've found that I can uninstal the printer, then plug the printer in, HPLIP detects it and voilá, it'll print.
Sometimes, the program will show a message HPLIP already mounted, so that might be part of the problem.
Also, HPLIP creates a 'system problem', but the report never goes anywhere...
I'd like to be able to troubleshoot this problem, or should I just wait until a new version of HPLIP is released. I think this problem affects more people.
Edit: Forgot to mention. When plugging the printer in, HPLIP will add another printer instead of recognising that the printer is already installed.
Status update: Solved The problem was the HPLIP download. I downloaded version 3.12.4, but the correct version is 3.12.2... as indicated by HPLIP... but the link goes to the next version.
I uninstalled everything. Installed 3.12.2. In the end it all works.