Hello Derek Cunningham, I am an HP Support Engineer. I am speaking for myself and not for HP but I believe that I can assist you.
Well, it took some digging. The last firmware release that I could find was bit release August 2, 2003 (version 1.040.2) part # C4168-67907 listed as "KIT-ROC DIMM HPCS". That said, as of March 31, 2009 the product no longer has support and service parts may no longer be available. I gathered this information per your request directly - however, don't believe that updating the firmware will resolve the "page spew" issue reported. I went through the firmware fix list for the various firmware DIMM releases and didn't see anything matching your symptomatic behavior.
If your print work-flow is point-and-print (clients printing through a print server) please ensure the server and clients drivers match. You can always remove the client printer connection and reestablish to ensure the matching binaries vend. Version of driver is important as older device specific drivers would not be supported or even stable with current operating systems. I would suggest switching to the Microsoft OS inbox driver for testing.
Suggestions were made to try PCL 5 or PS, I think the critical thing here is to ensure you are using the latest available driver for your product and OS.