I have suffered the same sort of problem for about a month now. After a bit of really frustrating searching around, including on these forums, I have found a fix that worked for me. I cannot take credit for the actual fix, please see the article at the following link:
http://www.alexfalkenberg.com/2009/10/06/linkstation-windows-printing-problem-solved/
Follow the instructions in the article and the linked Microsoft Support HOW-TO page, and you should be up and printing again.
One note; when you get as far as specifying your "Name or address of server providing lpd:" and "Name of printer or print queue on that server", you will enter the networking name (HS-DHGL###) and "lp", respectively. I am running XP Pro SP3, and there may be minor variance in what these fields are called on other versions of Windows. No slashes, forward, reverse, or otherwise, should be entered into these fields.
On a positive note, this also appears to get rid of the annoying "Remote Downlevel Document", or whatever it was called, being left in the print queue all the time. Not that it ever made much difference...
On a negative note, it appears I formatted/reformatted, initialized, updated firmware, etc., and deleted all my shared files for nothing. If you did the same during your troubleshooting, and are having strange circular reference problems with "pictures" and/or "usbdisk1" folders on your NAS, disable "PCast" and reformat your drive(s) again to fix this error.
Finally, two closing comments:
1. BUFFALO, shame on you for incorporating such a flimsy print server into so many of your products. This print server / utility barely supports Windows printing, which is without a doubt the most common method of printing in the technical world. We as consumers should not have to rely on private individuals to patch your shoddy software/hardware. However, now that someone has fixed the problem for you, how about you incorporate this fix in a firmware / software update for all your consumers that are suffering now, or soon will be?
2. Thank you, Alex Falkenberg / alexfalkenberg.com for providing a fix to my and likely so many other BUFFALO NAS users' printing problems.
My setup: NAS - BUFFALO LinkStation Live HS-DH500GL, firmware 2.11v101b (2.10 before this incident), USB Disk 1 - BUFFALO DriveStation HD-CE1.0TU2, USB printer - Canon imageCLASS D340
I hope this helps!!