The ISDN changes for the HISAX drivers
that came in since test12 have introduced a bug that causes a 
AIEE-something and a complete kernel hang when i hangup the isdn line.
I have reversed the patch for all occurences of INIT_LIST_HEAD in the 
isdn patch part and it works for me now.

The relevant part is attached. Please back it out for 2.4.0.

Happy new year

Gerold Jury