[hsflinux] Modem problem 'pppd died unexpectedly'

[Marc Knorpp]

Hy folks!

I have a problem and did not find a way out!

It's a P166 PC with intern PCI Modem and Mandrake 8.2 running
 properly on it.
(Now I know that this type of Modems are very tricky to install,
 but I won't give up at all!)

After some starting problems I found the conexant HSF Drivers
 for the Modem and got the Card working fine.

I connect to a CallbyCall Provider via minicom or kppp (what I prever).

To start the connection is no problem, but after a little while the 
connection stops with two error messages( when it stops that's
 different, some seconds or some minutes):

'pppd died unexpectedly'

and from kppp: 'Error 16' that means:
'The link was terminated by the modem hanging up'

I've googled dozens of Threads and found lots of Information to this 
problem and solutions that are:

1. no Text in  /etc/ppp/options
2. the User must be in the groups:'dialout' and 'uucp'
3. checking (use dmesg)if pppd is installed properly
4. rights for the user:
-kppp x
-pppd x
-/dev/ttS7 rw
-/etc/resolf.conf rw
-/var/lock rw
-/etc/ppp/options r
-/var/log/messages r

I think I checked everything of this list, but it doesn't work at all!
What could this be?

Marc