mISDN with Capisuite seems to crash after kernel-update

Hello everybody,

my system is an Ubuntu 12.04 LTS, nowadays running kernel 
3.2.0-90-generic-pae, attached to it is an USB Draytek Minivigor ISDN 
adapter.

Before upgrading to my current kernel version, mISDN and Capisuite 
providing answering machine and fax services worked without a flaw.

But with the new kernel after receiving a phone call the mISDN-system 
seems to crash. This is what I get from the logfiles:

______________________

capisuite.log:
Sun Dec 20 11:00:43 2015 Connection 0xb5900478: Connection object 
created for incoming call PLCI 257 from XXXXXXXXX to XXXXXXXXX CIP 0x10
Sun Dec 20 11:00:43 2015 Connection 0xb5900478: call from XXXXXXXXX to 
XXXXXXXXX for sendfax connecting with fax
Sun Dec 20 11:00:43 2015 Connection 0xb5900478: accepting with service 1.
______________________

capisuite.error:
Sun Dec 20 11:03:15 2015 CapiSuite 0xb5900478: ERROR: Connection 
0xb5900478: Error in readMessage(), message: CapiError: read Message 
called but no message available? occured in CAPI::readMessage()
______________________

mISDNcapi.log
Dec 20 10:58:50.563312 I         daemon.c:2212 main(01724):Init mISDN 
lib version 20005, debug = 0 (0)
Dec 20 10:58:50.564260 I         daemon.c:2224 main(01724):Did set eGID 
to dialout gid:20
Dec 20 10:58:50.564317 I      mc_buffer.c:  40 
mc_buffer_init(01724):Setup mc buffer MI_MCBUFFER_DEBUG
Dec 20 10:58:50.688725 I         daemon.c:1973 
main_loop(01725):mIControl added to idx 0
Dec 20 10:58:50.688816 I         daemon.c:1980 main_loop(01725):mIsock 
added to idx 1
Dec 20 10:58:50.688837 I         daemon.c:1987 
main_loop(01725):mICAPItimer added to idx 2
Dec 20 10:58:50.688855 I         daemon.c:1995 main_loop(01725):mCsock 
added to idx 3
Dec 20 10:58:50.734216 E         capi20.c: 171 
capi_dump_shared(01725):MapAddress: 0xb73c1000
Dec 20 10:58:50.734266 E         capi20.c: 172 
capi_dump_shared(01725):MapSize:    86028
Dec 20 10:58:50.734296 E         capi20.c: 184 
capi_dump_shared(01725):Semaphore: 1 (ret=0)
Dec 20 10:58:50.734318 E         capi20.c: 186 
capi_dump_shared(01725):Shared memory initialized
Dec 20 10:58:50.734337 E         capi20.c: 187 
capi_dump_shared(01725):Usage count: 2
Dec 20 10:58:50.734355 E         capi20.c: 188 
capi_dump_shared(01725):Max used Id: 0
Dec 20 10:58:50.734381 E         capi20.c: 198 
capi_dump_shared(01725):End of dump
Dec 20 10:58:50.734639 E         capi20.c: 171 
capi_dump_shared(01725):MapAddress: 0xb73c1000
Dec 20 10:58:50.734672 E         capi20.c: 172 
capi_dump_shared(01725):MapSize:    86028
Dec 20 10:58:50.734692 E         capi20.c: 184 
capi_dump_shared(01725):Semaphore: 1 (ret=0)
Dec 20 10:58:50.734711 E         capi20.c: 186 
capi_dump_shared(01725):Shared memory initialized
Dec 20 10:58:50.734729 E         capi20.c: 187 
capi_dump_shared(01725):Usage count: 2
Dec 20 10:58:50.734746 E         capi20.c: 188 
capi_dump_shared(01725):Max used Id: 0
Dec 20 10:58:50.734764 E         capi20.c: 198 
capi_dump_shared(01725):End of dump
Dec 20 10:58:50.734907 I         daemon.c:1698 
mIcapi_register(01725):register application id 1 fd=12
Dec 20 10:58:50.735199 I layer3/mlayer3.c:  98 open_layer3(01725):mISDN 
kernel version 1.01.21 found
Dec 20 10:58:50.735249 I layer3/mlayer3.c:  99 open_layer3(01725):mISDN 
user   version 1.01.31 found
Dec 20 10:58:50.735276 I layer3/mlayer3.c: 100 open_layer3(01725):mISDN 
library interface version 2 release 5
Dec 20 11:00:43.570669 W         daemon.c:1217 OpenBInstance(01737): 
LPLCI0101 Appl-001 *4: Error on MISDN_CTRL_RX_BUFFER  ioctl maybe kernel 
do not support it  - Invalid argument
Dec 20 11:00:43.572264 I         daemon.c: 929 BCthread(19030):Started 
Bchannel thread=19030
__________________

After this mISDN/Capisuite crash, no reaction on further calls until new 
boot.
I can remove/kill the modules/programs to a certain step, but hfcsusb is 
refusing to be removed, stating its still in use, "lsmod | grep hfcsusb" 
gives me "hfcsusb                36106  4294967295".

Pulling the current version of mISDN via GIT and compiling works without 
any problem, the problem persists.

Maybe there is somebody outside who can give me a hint where to look for 
the problem.

Thanks in advance!


Manuel