xscreensaver doesn't run on potato with 2.4.4 kernel

Hello,

xscreensaver 3.22 can't unlock the screen via pam on a stock
debian potato box with kernel 2.4.4 and the correspondig Adrian Bunk's
packages to run 2.4 on potato.

Here is a log of xscreensaver showing the problem:

The first time it locks the screen it authentificates  the
user via pam correctly:

xscreensaver: switching to visual 0x20 (TrueColor,   depth:
16, cmap:  64)
xscreensaver: saver window is 0x3000006.
xscreensaver: destroyed old saver window 0x3000001.
xscreensaver: spawning "qix -root -solid -delay 0 -segments
100" in pid 390.
xscreensaver: unblanking screen at Wed May  9 21:01:57 2001.
xscreensaver: killing pid 390.
xscreensaver: child pid 390 (qix) terminated with SIGTERM.
xscreensaver: ungrabbing mouse (was 0x25).
xscreensaver: ungrabbing keyboard (was 0x25).
xscreensaver: awaiting idleness.
xscreensaver: LOCK ClientMessage received; activating and
locking.
xscreensaver: locked mode switching.
xscreensaver: blanking screen at Wed May  9 21:02:04 2001.
xscreensaver: grabbing keyboard on 0x25... GrabSuccess.
xscreensaver: grabbing mouse on 0x25... GrabSuccess.
xscreensaver: vp is 1024x768+0+0.
xscreensaver: spawning "grav -root -trail -decay" in pid
391.
xscreensaver: suspending pid 391.
xscreensaver: prompting for password.
xscreensaver: child pid 391 (grav) stopped with SIGSTOP.
xscreensaver: grabbing server...
xscreensaver: ungrabbing mouse (was 0x25).
xscreensaver: grabbing mouse on 0x300000e... GrabSuccess.
xscreensaver: ungrabbing server.
xscreensaver: pam_start ("xscreensaver", "jesus", ...) ==> 0
(Success)
xscreensaver:   pam_set_item (p, PAM_TTY, ":0.0") ==> 0
(Success)
xscreensaver:     PAM ECHO_OFF("Password: ") ==> password
xscreensaver:   pam_authenticate (...) ==> 0 (Success)
xscreensaver: pam_end (...) ==> 0 (Success)
xscreensaver: password correct.
xscreensaver: grabbing server...


But the second time it can't authentificate via pam. It 
reverts to normal password checking and succeedes:

xscreensaver: ungrabbing mouse (was 0x300000e).
xscreensaver: grabbing mouse on 0x25... GrabSuccess.
xscreensaver: ungrabbing server.
xscreensaver: resuming pid 391.
xscreensaver: unblanking screen at Wed May  9 21:02:11 2001.
xscreensaver: killing pid 391.
xscreensaver: child pid 391 (grav) terminated with SIGTERM.
xscreensaver: ungrabbing mouse (was 0x25).
xscreensaver: ungrabbing keyboard (was 0x25).
xscreensaver: unlocked mode switching.
xscreensaver: awaiting idleness.
xscreensaver: LOCK ClientMessage received; activating and
locking.
xscreensaver: locked mode switching.
xscreensaver: blanking screen at Wed May  9 21:03:01 2001.
xscreensaver: grabbing keyboard on 0x25... GrabSuccess.
xscreensaver: grabbing mouse on 0x25... GrabSuccess.
xscreensaver: vp is 1024x768+0+0.
xscreensaver: spawning "bouboule -root" in pid 402.
xscreensaver: suspending pid 402.
xscreensaver: prompting for password.
xscreensaver: child pid 402 (bouboule) stopped with SIGSTOP.
xscreensaver: grabbing server...
xscreensaver: ungrabbing mouse (was 0x25).
xscreensaver: grabbing mouse on 0x3000089... GrabSuccess.
xscreensaver: ungrabbing server.
xscreensaver: pam_start ("xscreensaver", "jesus", ...) ==> 0
(Success)
xscreensaver:   pam_set_item (p, PAM_TTY, ":0.0") ==> 0
(Success)
xscreensaver:     PAM ECHO_OFF("Password: ") ==> password
xscreensaver: child pid 403 (<unknown>) exited abnormally
(code 0).
xscreensaver:   pam_authenticate (...) ==> 7 (Authentication
failure)
xscreensaver:   pam_set_item(p, PAM_USER, "root") ==> 0
(Success)
xscreensaver:     PAM ECHO_OFF("Password: ") ==> password
xscreensaver: child pid 404 (<unknown>) exited abnormally
(code 0).
xscreensaver:   pam_authenticate (...) ==> 7 (Authentication
failure)
xscreensaver: pam_end (...) ==> 0 (Success)
xscreensaver: authentication via PAM passwords failed.
xscreensaver: but authentication via normal passwords
succeeded.
xscreensaver: password correct.

Can anyone explain (and fix!) this?

TIA

Jesus Ruiz