I'm having the same issue. I'm running OS 10.8.2 with my HP 5MP using a USB to Parallel cable. After just about every print I have to reboot the printer, disconnect and reconnect, delete and reinstall the driver. All this to clear it out. I can't figure out where it's choking. I seem to have the latest HP drivers installed. It seems to be the same issue whether printing a PDF from Acrobat or from Preview, printing a web page, a word doc, etc.
Did either of you ever solve the problems you were having?
I came here hoping to get encouragement to finally ditch my 5MP, but I see that some people are still happily using them, so now I'm motivated to get mine up and running again.
Now I have to obtain a compatible USB-to-Parallel cable, possibly get printer drives manually, and see how things go?
I have spent months to get my HP Laserjet 5MP running with my new iMac.
The Mac kept loosing the connection to my printer, I always had to unplug it and reinstall it...
I went nuts !
I never had problems with my old Windows laptop !
Finally it was fairly easy:
I am using Mac OX X 10.7.5
I just bought a new USB-to-parallel-cable.
The Mac immediately recognized the USB cable.
After that I was able to install the printer as usual.
Maybe I need to say that I am using the latest HP driver package, so I could choose the right driver for the installation...
It is working happily ever since !
Looking back, it must have to do with the (wrong) USB cable, although I cant tell what exactly was wrong with my old cable.
What, pray tell, was the right USB-Parallel cable? The first one I tried never worked; the second one was erratic and finally became such a nuisance that I bought a cheap Brother printer. But it would nice to have the HP LaserJet 5MP as an emergency backup (having just gone through some odd problems).