[SLL] hplip intermittent printer problem

[ter]

The printer is an HP multifunction laserjet. The server is running
lenny, with its standard cups/hplip setup. The printing function worked
fine for a long time with etch. After the upgrade to lenny, everything
still worked, except occasionally, sometimes as rare as once in a week,
sometimes several times a day, there would be junk, usually ending in
lines with black blocks. It can happen between print jobs, or sometimes
in the middle of a print job. When this happens, the syslog shows this
error message:

prnt/backend/hp.c 594: ERROR: 30010 other; will retry in 30 seconds

hp.c is in hplip. code 594 is apparently some kind of transitory HP
internal printer error status, the precise nature of which is
ungooglable, except for one mention at hp.com. From hp.c, it looks like
for each printing request, hplip checks the printer for transitory error
status like 594 and others, then sleeps 30 secs and loops till the
condition clears. If it doesn't clear in 30 seconds, there would be
another such message. So the fact that there is only one such message
every time the printing goes awry means the transitory error has cleared
- except that this error is always followed by junk being printed. The
junk printing usually clears at the end of the print job which both cups
and hplip reports as being successful. If I run hp-toolbox, which
monitors the printer status, it gives a correlated status of "busy"
before reporting successful print job completion.

I am stumped. There was a redhat bug report on upstream hplip that seems
to have some commonality with this problem, but not exactly. I am not
sure it has to do with the upgrade to hplip in Lenny, I am not sure it
is a bug.

Has anybody else run into this, or heard of it?