asterisk users - Jan 2008 - No more audio with 99777 SVN version in certain case

Hi,

we have an Debian Etch 4.0 amd64 server with 2 B410P cards. Asterisk SVN 
r99777 is installed. We tried with mISDN shipped with Asterisk/Zaptel 
(make b410p) as well as with the latest version from mISDN.org 1.1.7.2. 
zaptel, ztdummy and crt-ccitt modules are loaded. Output of /dev/zap is:

root at SrvPhone:~# ls -al /dev/zap
total 0
drwxr-xr-x  2 root root      120 2008-01-23 16:42 .
drwxr-xr-x 17 root root     4400 2008-01-23 16:54 ..
crw-rw----  1 root root 196, 254 2008-01-23 16:42 channel
crw-rw----  1 root root 196,   0 2008-01-23 16:42 ctl
crw-rw----  1 root root 196, 255 2008-01-23 16:42 pseudo
crw-rw----  1 root root 196, 253 2008-01-23 16:42 timer

The problem we face is following:

- start Asterisk
- enter in a meetme conf from a SIP Phone -> OK, we have "Enter PIN 
Number" and then "You're the only person ..." and then MOH
- now we call from outside through ISDN and want to enter the conf -> we 
hear few words  from "Enter your PIN number" (sometimes all the 
sentance) and then *no more* audio in all Asterisk, for all devices. 
Sometimes break is created when ISDN party hangup, which means that all 
the conference went OK.

It's now anymore possible to enter conferences or to call voicemails 
_from any device_: on CLI we see that everything is OK, but silence. 
Calling from a device to another, SIP iAX or ISDN, is working. Only 
solution to get it work again is to restart Asterisk.

The problem appears since this week when we updated from an old SVN 
version (05/2007).

Thanks for any help.

-- 
Daniel