Specified port cannot be added. The request is not supported

I'm faced with the above error message on a WindowsXP Media Center
installation. Version 2002 wit Sp2.

- I've checked registry settings of port monitor "localspl.dll".
- I've checked version of localspl.dll
- I've checked wether or not a second version of localspl.dll exists on the
system.
- I'm not connected through a terminal session (at least I assume so).

The thing I'm not able to understand is, that I can add a local port through
"AddPortEx" function of winspool.drv as well as through "XcvData" through a
small test application. The above mentioned error message only appear if the
user creates the local port through Printer & Faxes > Serverproperties > Add
port, or through add priner wizard.

I've read in some ng archives quite similar posts, but none of them has been
solved. Has anybody ever solved the above described issue.

Kind regards, Lela