PulseAudio cannot detect my soundcard (sometimes)

Binary package hint: pulseaudio

1) andrea@andrea-laptop:~$ lsb_release -rd
Description: Ubuntu karmic (development branch)
Release: 9.10

2) andrea@andrea-laptop:~$ apt-cache policy pulseaudio
pulseaudio:
  Installed: 1:0.9.19-0ubuntu3
  Candidate: 1:0.9.19-0ubuntu3
  Version table:
 *** 1:0.9.19-0ubuntu3 0
        500 http://archive.ubuntu.com karmic/main Packages
        100 /var/lib/dpkg/status

3) I expect my soundcard to be detected after a normal boot and I expect PulseAudio mixer can display it

4) Sometimes (yes, only sometimes, it doesn't happen always) PulseAudio can't detect my sound card, and this is what I see in PulseAudio mixer: http://img2.imageshack.us/img2/5295/soundpreferences.jpg

5) Here you can find more informations about my soundcard device:

andrea@andrea-laptop:~$ lshw -C multimedia
WARNING: you should run this program as super-user.
  *-multimedia
       description: Audio device
       product: 82801I (ICH9 Family) HD Audio Controller
       vendor: Intel Corporation
       physical id: 1b
       bus info: pci@0000:00:1b.0
       version: 03
       width: 64 bits
       clock: 33MHz
       capabilities: bus_master cap_list
       configuration: driver=HDA Intel latency=0
       resources: irq:21 memory:f6500000-f6503fff

andrea@andrea-laptop:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC888 Analog [ALC888 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC888 Digital [ALC888 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 3: NVIDIA HDMI [NVIDIA HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

andrea@andrea-laptop:~$ lspci
00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07)
00:01.0 PCI bridge: Intel Corporation Mobile 4 Series Chipset PCI Express Graphics Port (rev 07)
00:1a.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 03)
00:1a.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 03)
00:1a.2 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 03)
00:1a.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 03)
00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)
00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 03)
00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 03)
00:1c.2 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 3 (rev 03)
00:1c.3 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 4 (rev 03)
00:1c.4 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 5 (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 03)
00:1d.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 03)
00:1d.2 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 03)
00:1d.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 93)
00:1f.0 ISA bridge: Intel Corporation ICH9M LPC Interface Controller (rev 03)
00:1f.2 SATA controller: Intel Corporation ICH9M/M-E SATA AHCI Controller (rev 03)
00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 03)
01:00.0 VGA compatible controller: nVidia Corporation G96 [GeForce 9600M GT] (rev a1)
02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8071 PCI-E Gigabit Ethernet Controller (rev 16)
03:00.0 Network controller: Intel Corporation Wireless WiFi Link 5100

p.s: feel free to ask me more information if you need them to fix this bug.