i did a clean install on ubuntu 12.10. Everything seemed fine at first including sound but after a while it stopped working. To get is back i have to restart it, sometimes even more than once.

Any idea on how to fix this?

sudo aplay -L

default
    Playback/recording through the PulseAudio sound server
sysdefault:CARD=PCH
    HDA Intel PCH, ALC665 Analog
    Default Audio Device
front:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    Front speakers
surround40:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Digital
    IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=PCH,DEV=0
    HDA Intel PCH, HDMI 0
    HDMI Audio Output
dmix:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    Direct sample mixing device
dmix:CARD=PCH,DEV=1
    HDA Intel PCH, ALC665 Digital
    Direct sample mixing device
dmix:CARD=PCH,DEV=3
    HDA Intel PCH, HDMI 0
    Direct sample mixing device
dsnoop:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    Direct sample snooping device
dsnoop:CARD=PCH,DEV=1
    HDA Intel PCH, ALC665 Digital
    Direct sample snooping device
dsnoop:CARD=PCH,DEV=3
    HDA Intel PCH, HDMI 0
    Direct sample snooping device
hw:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    Direct hardware device without any conversions
hw:CARD=PCH,DEV=1
    HDA Intel PCH, ALC665 Digital
    Direct hardware device without any conversions
hw:CARD=PCH,DEV=3
    HDA Intel PCH, HDMI 0
    Direct hardware device without any conversions
plughw:CARD=PCH,DEV=0
    HDA Intel PCH, ALC665 Analog
    Hardware device with all software conversions
plughw:CARD=PCH,DEV=1
    HDA Intel PCH, ALC665 Digital
    Hardware device with all software conversions
plughw:CARD=PCH,DEV=3
    HDA Intel PCH, HDMI 0
    Hardware device with all software conversions