cups hanging when initializing backend

[Hatto von Hatzfeld]

My cups server quite often (not always) fails to initialize the printer
connected to /dev/lp0 ("Backend did not respond within 30 seconds!").

In this cases none of the printers can be used, because the cups server
itself denies all requests (even http://localhost:631/).

I made the server "verbose", but cannot get more helpful information than
the phrase "Backend did not respond within 30 seconds!".

Here my configuration:

(some lines from /etc/cups/printers.conf)

<Printer HPColor>
Info HP Color LaserJet 3700
DeviceURI lpd://192.168.5.98:515/LPT1
....
</Printer>
<DefaultPrinter hplaserjet1200>
Info HP LaserJet 1200 generic PS
DeviceURI parallel:/dev/lp0
....
</Printer>
<Printer hplj1200>
Info HP LaserJet 1200 Series PS
DeviceURI parallel:/dev/lp0
....
</Printer>
<Printer MFKv2>
Info Faxscanprinter MFKv2
DeviceURI lpd://192.168.5.243/printer
....
</Printer>

The difference between both printer queues of HP LJ 1200 is, that the first
is configured/filtered as "Foomatic/pxlmono (recommended)", the second as
"Foomatic/Postscript". The second is used for print jobs coming from a
Windows PC via Samba (which works fine if the cups server does not fail to
initialize).

OS: SuSE 9.2 (with Kernel 2.6.8-24.18-default and KDE 3.4.2 Level "a")

CUPS: cups-1.1.21-5.6

What is wrong?

Ciao,
Hatto