HSF modem driver corrupts system

>From /var/log/messages:

Mar  5 08:10:44 system pppd[27208]: Hangup (SIGHUP)
Mar  5 08:10:44 system pppd[27208]: Modem hangup
Mar  5 08:10:44 system pppd[27208]: Connection terminated.
Mar  5 08:10:44 system BUG: unable to handle kernel NULL pointer dereference at 0000005c
Mar  5 08:10:44 system IP: [<c011364f>] __wake_up_common+0x10/0x52
Mar  5 08:10:44 system *pde = 00000000
Mar  5 08:10:44 system Oops: 0000 [#1] PREEMPT
Mar  5 08:10:44 system Modules linked in: hsfusbcd2 hsfmc97sis hsfmc97ati hsfmc97ali hsfmc97via hsfmc97ich hsfpcibasic3 hsfpcibasic2 hsfserial hsfengine(P) hsfosspec hsfsoar [last unloaded: hsfosspec]
Mar  5 08:10:44 system
Mar  5 08:10:44 system Pid: 14374, comm: khsfd/modem Tainted: P          (2.6.27-gentoo-r8 #3)
Mar  5 08:10:44 system EIP: 0060:[<c011364f>] EFLAGS: 00010092 CPU: 0
Mar  5 08:10:44 system EIP is at __wake_up_common+0x10/0x52
Mar  5 08:10:44 system EAX: 0000005c EBX: efea6000 ECX: 00000001 EDX: 00000001
Mar  5 08:10:44 system pppd[27208]: Exit.
Mar  5 08:10:44 system ESI: 00000000 EDI: 00000001 EBP: 00000020 ESP: efea7ec8
Mar  5 08:10:44 system DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068
Mar  5 08:10:44 system Process khsfd/modem (pid: 14374, ti=efea6000 task=ed08c000 task.ti=efea6000)
Mar  5 08:10:44 system Stack: 00000001 0000005c efea6000 00000000 00000206 00000020 c0115216 00000000
Mar  5 08:10:44 system 00000000 00000000 00000126 efeaf9c4 f884c8e1 00000000 000b0001 efe6380c
Mar  5 08:10:44 system f8850a40 00000000 00050002 efeaf9c4 efeaf9c0 efe6381c efeaf9c4 efea7f64
Mar  5 08:10:44 system Call Trace:
Mar  5 08:10:44 system [<c0115216>] __wake_up+0x1d/0x3d
Mar  5 08:10:44 system [<f884c8e1>] cnxt_event_handler+0x1ba/0x2e2 [hsfserial]
Mar  5 08:10:44 system [<fc593ea3>] hsfengine1972_+0x433/0x560 [hsfengine]
Mar  5 08:10:44 system [<c012b045>] getnstimeofday+0x4a/0xca
Mar  5 08:10:44 system [<fc592a41>] hsfengine1787_+0x1c1/0x200 [hsfengine]
Mar  5 08:10:44 system [<f88601ed>] TimerThreadFunction+0x26/0x7b [hsfosspec]
Mar  5 08:10:44 system [<f885f955>] cnxt_thread+0x16b/0x1eb [hsfosspec]
Mar  5 08:10:44 system [<c0114f38>] default_wake_function+0x0/0x8
Mar  5 08:10:44 system [<f885f7ea>] cnxt_thread+0x0/0x1eb [hsfosspec]
Mar  5 08:10:44 system [<c0102f47>] kernel_thread_helper+0x7/0x10
Mar  5 08:10:44 system =======================
Mar  5 08:10:44 system Code: 4c c1 50 c0 eb 0c 01 1d 58 c1 50 c0 11 15 5c c1 50 c0 5b c3 8b 80 48 01 00 00 c3 55 57 56 53 83 ec 08 89 44 24 04 89 14 24 89 cf <8b> 18 83 eb 0c 8b 73 0c eb 25 8b 2b ff 74 24 20 8b 4c 24 20 8b
Mar  5 08:10:44 system EIP: [<c011364f>] __wake_up_common+0x10/0x52 SS:ESP 0068:efea7ec8
Mar  5 08:10:44 system ---[ end trace 740556cd45400aa8 ]---
Mar  5 08:10:44 system note: khsfd/modem[14374] exited with preempt_count 1
Mar  5 08:18:00 system shutdown[28240]: shutting down for system halt
Mar  5 08:18:04 system init: Switching to runlevel: 0
Mar  5 08:18:09 system sshd[3695]: Received signal 15; terminating.
Mar  5 08:21:39 system usbcore: deregistering interface driver hsfusbcd2
Mar  5 08:21:39 system 0155923.840: <7>+StatMgr_Close: Client efe6381c left
Mar  5 08:21:39 system cnxthsf_OsDestroyPeriodicTimer: task queue stuck?!
Mar  5 08:21:39 system OsThreadStop: kill_proc osthrd->pid=14374 r=-3
Mar  5 08:21:39 system shutdown[29248]: shutting down for system halt
Mar  5 08:21:45 system shutdown[29250]: shutting down for system halt
Mar  5 08:21:49 system shutdown[29252]: shutting down for system halt
Mar  5 08:21:55 system shutdown[29254]: shutting down for system halt

As you might guess from that last few lines, the system has become
so corrupted that the shutdown command no longer works (requiring
the use of the on/off switch to restart the machine.