no usb or lpt1 devices

[R. Sheng-Chieh Cheng]

Background: I have a Samsung ML-2510 monochrome laser printer.
Initially I used CUPS and it did not work (maybe too new for
this old distro).  So I downloaded the Unified Linux Driver
from Samsung's website,

http://www.samsung.com/us/consumer/detail/support.do?group=printersmultifunction&type=printersmultifunction&subtype=monochromelaserprinters&model_nm=ML-2510&language=&cate_type=all&dType=D&mType=DR&vType=&prd_ia_cd=06010400&disp_nm=ML-2510&model_cd=ML-2510/XAA&menu=download

Installed it on the desktop and everything worked fine.

Shutdown for the night and the next day, it doesn't work.  Deleted the printer
and try coping off the PPD and raster files as in

http://openprinting.org/show_printer.cgi?recnum=Samsung-ML-2510
(scroll down 4/5)
(This approach works fine on my laptop).

Then used CUPS admistration to add an new printer.  Enter name, location, and
description -> continue.  The USB or LPT1 port does not show up in the device
list (it did for the laptop).  It seems as if something (due to Samsung's
Unified Linux Driver) is holding onto the USB.

I need the desktop to "let go" of the USB and LPT1 devices.  How do I do this?

Thank in advance for any help.

Sheng-Chieh