I have had serious problems trying to print to an HP network printer using CUPS and hplip. The printer gets spontaneously disabled after printing something, then I have to turn off both the computer and printer to get it working again. Doing things like clearing the spool and cupsenable or restarting cups do not improve the situation. It is some kind of "backend" problem. The cups error log shows no errors, just "information" that there was a backend failure. The printing is raw so it does involve a filter and it uses a network socket method to connect:
How can I figure out what is going wrong on the backend and stop the printer from stalling?