How to resume the connection?

[Strong]

Sometimes my modem brakes up the connection, i don't know how to resume
it.
I establish it with ifup-ppp and brake with ifdown-ppp. But when this
break up happens ifup-ppp is still in the RAM and on ifdown-ppp does not
obey. On kill i see ifup-ppp <defunct> - at ps -A. kill -9 doesn't help.
Only by rebooting the system it helps. How to solve?
After connection has been broken i see the following
in /var/log/messages:
Aug 18 01:35:43 STNhome kernel: usb 3-2: USB disconnect, address 4
Aug 18 01:35:43 STNhome pppd[3106]: Modem hangup
Aug 18 01:35:43 STNhome pppd[3106]: Connection terminated.
Aug 18 01:35:43 STNhome pppd[3106]: Connect time 1.1 minutes.
Aug 18 01:35:43 STNhome pppd[3106]: Sent 7816 bytes, received 55876
bytes.
Aug 18 01:35:43 STNhome
NET[3210]: /etc/sysconfig/network-scripts/ifdown-post :
updated /etc/resolv.conf
Aug 18 01:35:44 STNhome su(pam_unix)[3221]: session opened for user root
by (uid=0)
Aug 18 01:35:44 STNhome su(pam_unix)[3221]: session closed for user root
Aug 18 01:35:44 STNhome kernel: Unable to handle kernel NULL pointer
dereference at virtual address 00000000
Aug 18 01:35:44 STNhome kernel:  printing eip:
Aug 18 01:35:44 STNhome kernel: c020e7ce
Aug 18 01:35:44 STNhome kernel: *pde = 11f6b067
Aug 18 01:35:44 STNhome kernel: Oops: 0000 [#1]
Aug 18 01:35:44 STNhome kernel: Modules linked in: ppp_deflate
zlib_deflate ppp_async crc_ccitt ppp_generic slhc cdc_acm radeon drm md5
ipv6 w83627hf eeprom i2c_sensor i2c_isa ipt_REJECT ipt_state
ip_conntrack iptable_filter ip_tables video button battery ac uhci_hcd
ehci_hcd shpchp i2c_i801 i2c_core snd_intel8x0 snd_ac97_codec
snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device
snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd soundcore snd_page_alloc
ext3 jbd
Aug 18 01:35:44 STNhome kernel: CPU:    0
Aug 18 01:35:44 STNhome kernel: EIP:    0060:[<c020e7ce>]    Not tainted
VLI
Aug 18 01:35:44 STNhome kernel: EFLAGS: 00210246   (2.6.11-1.1369_FC4)
Aug 18 01:35:44 STNhome kernel: EIP is at get_kobj_path_length+0x19/0x31
Aug 18 01:35:44 STNhome kernel: eax: 00000000   ebx: 00000000   ecx:
ffffffff   edx: ffffffff
Aug 18 01:35:44 STNhome kernel: esi: 00000001   edi: 00000000   ebp:
df637cb8   esp: d6ab9e04
Aug 18 01:35:44 STNhome kernel: ds: 007b   es: 007b   ss: 0068
Aug 18 01:35:44 STNhome kernel: Process pppd (pid: 3106,
threadinfo=d6ab9000 task=d2ac5550)
Aug 18 01:35:44 STNhome kernel: Stack: 000000d0 df637c94 d3db9a18
df637cb8 c020e844 d3db9a00 df637c94 d3db9a18
Aug 18 01:35:44 STNhome kernel:        d9190988 c0288a86 c03e50e0
00000000 ffffffff ffffffff c03917b2 d6ab9e74
Aug 18 01:35:44 STNhome kernel:        c03917b3 d3db9a00 00000000
00000000 d3db9a00 c03e5440 cd81ac53 c0288a52
Aug 18 01:35:44 STNhome kernel: Call Trace:
Aug 18 01:35:44 STNhome kernel:  [<c020e844>] kobject_get_path+0xd/0x48
Aug 18 01:35:44 STNhome kernel:  [<c0288a86>] class_hotplug+0x34/0x1d1
Aug 18 01:35:44 STNhome kernel:  [<c0288a52>] class_hotplug+0x0/0x1d1
Aug 18 01:35:44 STNhome kernel:  [<c020f544>] kobject_hotplug
+0x1a8/0x396
Aug 18 01:35:44 STNhome kernel:  [<c020edd7>] kobject_release+0x0/0x8
Aug 18 01:35:44 STNhome kernel:  [<c020f822>] kref_put+0x24/0x82
Aug 18 01:35:44 STNhome kernel:  [<c01aac2c>] simple_unlink+0x3e/0x47
Aug 18 01:35:44 STNhome kernel:  [<c0288f60>] class_device_del+0xa6/0xc7
Aug 18 01:35:44 STNhome kernel:  [<c0288f89>] class_device_unregister
+0x8/0x10
Aug 18 01:35:44 STNhome kernel:  [<e09b1626>] acm_tty_close+0xb1/0xe3
[cdc_acm]
Aug 18 01:35:44 STNhome kernel:  [<c02590d4>] release_dev+0x157/0x977
Aug 18 01:35:44 STNhome kernel:  [<c0103894>] do_signal+0x8c/0x111
Aug 18 01:35:44 STNhome kernel:  [<c03748d1>] schedule_timeout
+0xdb/0x124
Aug 18 01:35:44 STNhome kernel:  [<c0259ee3>] tty_release+0x7/0xa
Aug 18 01:35:44 STNhome kernel:  [<c017c683>] __fput+0x4b/0xfa
Aug 18 01:35:44 STNhome kernel:  [<c017ae67>] filp_close+0x4f/0x6d
Aug 18 01:35:44 STNhome kernel:  [<c0103a51>] syscall_call+0x7/0xb
Aug 18 01:35:44 STNhome kernel: Code: 89 c6 85 c0 74 ee 89 d8 e8 67 0a
fc ff 89 f0 5b 5e c3 55 57 56 53 89 c5 be 01 00 00 00 31 db ba ff ff ff
ff 8b 7d 00 89 d1 89 d8 <f2> ae f7 d1 49 01 f1 8d 71 01 8b 6d 24 85 ed
75 e8 89 f0 5b 5e
Aug 18 01:35:46 STNhome ifup-ppp: pppd started for mf_gprs
on /dev/ttyACM0 at 115200
Aug 18 01:35:46 STNhome pppd[3240]: pppd 2.4.2 started by root, uid 0
Aug 18 01:35:46 STNhome pppd[3240]: Removed stale lock on ttyACM0 (pid
3106)
Aug 18 01:35:50 STNhome kernel:  <6>usb 3-2: new full speed USB device
using uhci_hcd and address 5
Aug 18 01:35:50 STNhome kernel: cdc_acm 3-2:1.0: ttyACM1: USB ACM device
-- 
Best regards,
Strong.