[cups.general] CUPS IPP Windows Printer appear Offline

[iCy-fLaME]

This problem might have been raised before, but I have been googling
for the past two days without much success.

Background:
I am running cups-1.2.4-9 on Fedora Core 6, just upgraded from FC4.
I have HP PSC 2355 installed and shared via IPP

What works:
All users can print, can cancel all print jobs (yes all of them in one
go), can pause printer.
The web interface works, using the web interface users can do all of
above and cancel individual print jobs.

Problem:
When the server was on FC4, Windows users used to be able to open
their printer queue (control panel -> Printer -> IPP printer) see all
the print jobs in queue and pause/resume/delete any print jobs.

After the upgrade to FC6 (and of course upgrade to cups 1.2.4),
windows users can no longer see the printer status as "Ready". Printer
status is always "offline", and "Error processing command." always
appear on the status bar of the printer queue window.

While Windows users still able to send jobs to the printer, their job
(or anyone elses) would never appear on their queue window, and hence
wont be able to cancel them.

Remarks:
While it is possible for user to use the web interface, it is not
practical at least in my case to teach every users to use the web
interface.

I never tried printing over SMB, but probably never will, because I
need a network printing solutions that can work over different
subnets. One of the design goal of my server is to rely only on TCP/IP
connections.

This could well be a Windows bug, rather than CUPS problem. But my
concern is, it worked before, so is there a way to work around the
problem to fool it to work again?

I am happy to supply logs and conf files if necessary.

iCy