Print problems E332n on Kubuntu

[Gus Zernial]

I have Kubuntu 9.04 with a custom 2.6.28.9 kernel. My printer
is a Lexmark E332n. My PPD file is a modified version of that
for mac OS/X, as apparently there is no E332n PPD for Linux.

Printing with this setup has worked for some time, but recently
print jobs periodically started failing. Simply - no print. I have
tried canceling the failed print jobs, restarting the CUPS daemon
and deleting/reinstalling the printer. After the delete/reinstall
it will work for a while, then fail again. Sample output from
/var/log/cups/error_log for a failed job is:

E [09/Nov/2009:16:55:11 -0800] [Job 741] May not be a PDF file (continuing anyway)
E [09/Nov/2009:16:55:11 -0800] [Job 741] PDF file is damaged - attempting to reconstruct xref table...
E [09/Nov/2009:16:55:11 -0800] [Job 741] Couldn't find trailer dictionary
E [09/Nov/2009:16:55:11 -0800] [Job 741] Couldn't read xref table
E [09/Nov/2009:16:55:11 -0800] PID 30441 (/usr/lib/cups/filter/pdftopdf) stopped with status 1!
E [09/Nov/2009:16:55:11 -0800] [Job 741] pdftops filter exited with status 1!
E [09/Nov/2009:16:55:11 -0800] [Job 741] Empty print file!
E [09/Nov/2009:16:55:11 -0800] PID 30442 (/usr/lib/cups/filter/cpdftocps) stopped with status 1!
E [09/Nov/2009:16:55:16 -0800] [Job 741] Job stopped due to filter errors.
E [09/Nov/2009:18:06:13 -0800] PID 5574 (/usr/lib/cups/filter/pstopdf) stopped with status 127!

BTW this is *not* a PDF job - it is a (Thunderbird) email.
Would appreciate help .....