I've tried that - it still insists on an administrator login to the web interface to re-enable the printer.Just set error policy = retry-job (rather than stop-printer) in the printer options for your printer. It will then keep retrying until the problem goes away. Obviously there's also a problem which causes the queue to be disabled (e.g. printer switched off or out of paper), which you might need to look at separately.
I notice that I can use xsane with the same USB device (it is a multi-function) immediately after starting the computer. It is only when I want to print that I get problems. That makes me suspect that the low level USB modules are not at fault.
Can you suggest any other troubleshooting commands that should be run, either by myself or anyone else who stumbles across this bug report? I realise there is a possibility that cups is not the culprit (maybe it is the kernel module or something in the hplip package), but I'm not sure how to pin down the root cause.