Win 7: Computer spielt auf einmal keinen Sound mehr ab

Überprüfung mit dxdiag, geht so:
http://www.youtube.com/watch?v=jIKRtm7Z3LI

Oder auch mal ein Live-System starten, Knoppix oder Ubuntu z.B., um die Hardware zu testen.

Falls der onBoard-Soundchip im Eimer ist, besorge dir eine PCI-Soundkarte und baue diese ein.

dxdiag:
 

------------------

------------
DxDiag Notes
------------
      Display Tab 1: No problems found.
        Sound Tab 1: No problems found.
        Sound Tab 2: No problems found.
          Input Tab: No problems found.

--------------------
DirectX Debug Levels
--------------------
Direct3D:    0/4 (retail)
DirectDraw:  0/4 (retail)
DirectInput: 0/5 (retail)
DirectMusic: 0/5 (retail)
DirectPlay:  0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow:  0/6 (retail)

-------------
Sound Devices
-------------
            Description: Realtek Digital Output(Optical) (Realtek High Definition Audio)
 Default Sound Playback: Yes
 Default Voice Playback: Yes
            Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0888&SUBSYS_10250344&REV_1002
        Manufacturer ID: 1
             Product ID: 100
                   Type: WDM
            Driver Name: RTKVHD64.sys
         Driver Version: 6.00.0001.6449 (English)
      Driver Attributes: Final Retail
            WHQL Logo'd: Yes
          Date and Size: 8/30/2011 17:28:46, 3069032 bytes
            Other Files:
        Driver Provider: Realtek Semiconductor Corp.
         HW Accel Level: Basic
              Cap Flags: 0xF1F
    Min/Max Sample Rate: 100, 200000
Static/Strm HW Mix Bufs: 1, 0
 Static/Strm HW 3D Bufs: 0, 0
              HW Memory: 0
       Voice Management: No
 EAX(tm) 2.0 Listen/Src: No, No
   I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No

            Description: Realtek Digital Output (Realtek High Definition Audio)
 Default Sound Playback: No
 Default Voice Playback: No
            Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0888&SUBSYS_10250344&REV_1002
        Manufacturer ID: 1
             Product ID: 100
                   Type: WDM
            Driver Name: RTKVHD64.sys
         Driver Version: 6.00.0001.6449 (English)
      Driver Attributes: Final Retail
            WHQL Logo'd: Yes
          Date and Size: 8/30/2011 17:28:46, 3069032 bytes
            Other Files:
        Driver Provider: Realtek Semiconductor Corp.
         HW Accel Level: Basic
              Cap Flags: 0xF1F
    Min/Max Sample Rate: 100, 200000
Static/Strm HW Mix Bufs: 1, 0
 Static/Strm HW 3D Bufs: 0, 0
              HW Memory: 0
       Voice Management: No
 EAX(tm) 2.0 Listen/Src: No, No
   I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No

---------------------
Sound Capture Devices
---------------------
-------------------
DirectInput Devices
-------------------
      Device Name: Maus
         Attached: 1
    Controller ID: n/a
Vendor/Product ID: n/a
        FF Driver: n/a

      Device Name: Tastatur
         Attached: 1
    Controller ID: n/a
Vendor/Product ID: n/a
        FF Driver: n/a

      Device Name: USB Multimedia Keyboard
         Attached: 1
    Controller ID: 0x0
Vendor/Product ID: 0x04CA, 0x002F
        FF Driver: n/a

      Device Name: USB Multimedia Keyboard
         Attached: 1
    Controller ID: 0x0
Vendor/Product ID: 0x04CA, 0x002F
        FF Driver: n/a

      Device Name: USB Multimedia Keyboard
         Attached: 1
    Controller ID: 0x0
Vendor/Product ID: 0x04CA, 0x002F
        FF Driver: n/a

      Device Name: Mass Storage Device
         Attached: 1
    Controller ID: 0x0
Vendor/Product ID: 0x058F, 0x6363
        FF Driver: n/a

Poll w/ Interrupt: No

-----------
USB Devices
-----------
+ USB-Root-Hub
| Vendor/Product ID: 0x8086, 0x3B34
| Matching Device ID: usb\root_hub20
| Service: usbhub
|
+-+ Generic USB Hub
| | Vendor/Product ID: 0x8087, 0x0020
| | Location: Port_#0001.Hub_#0002
| | Matching Device ID: usb\class_09
| | Service: usbhub

--------------
System Devices
--------------

     Name: High Definition Audio-Controller
Device ID: PCI\VEN_8086&DEV_3B56&SUBSYS_03441025&REV_06\3&11583659&0&D8
   Driver: n/a

     Name: High Definition Audio-Controller
Device ID: PCI\VEN_10DE&DEV_0BE2&SUBSYS_1141174B&REV_A1\4&187086D4&0&0108
   Driver: n/a

Audio Compressors:
WM Speech Encoder DMO,0x00600800,1,1,WMSPDMOE.DLL,6.01.7600.16385
WMAudio Encoder DMO,0x00600800,1,1,WMADMOE.DLL,6.01.7600.16385
IMA ADPCM,0x00200000,1,1,quartz.dll,6.06.7601.17514
PCM,0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode1),0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode2),0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode3),0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode1+),0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode2+),0x00200000,1,1,quartz.dll,6.06.7601.17514
Ogg Vorbis (mode3+),0x00200000,1,1,quartz.dll,6.06.7601.17514
Microsoft ADPCM,0x00200000,1,1,quartz.dll,6.06.7601.17514
GSM 6.10,0x00200000,1,1,quartz.dll,6.06.7601.17514
Messenger Audio Codec,0x00200000,1,1,quartz.dll,6.06.7601.17514
CCITT A-Law,0x00200000,1,1,quartz.dll,6.06.7601.17514
CCITT u-Law,0x00200000,1,1,quartz.dll,6.06.7601.17514
AC-3 ACM Codec,0x00200000,1,1,quartz.dll,6.06.7601.17514
MPEG Layer-3,0x00200000,1,1,quartz.dll,6.06.7601.17514

WDM Streaming Capture Devices:
Realtek HD Audio Front Mic input,0x00200000,1,1,ksproxy.ax,6.01.7601.17514
Realtek HD Audio Line input,0x00200000,1,1,ksproxy.ax,6.01.7601.17514
Realtek HD Audio Mic input,0x00200000,1,1,ksproxy.ax,6.01.7601.17514
Realtek HD Audio Stereo input,0x00200000,1,1,ksproxy.ax,6.01.7601.17514

WDM Streaming Rendering Devices:
Realtek HD Audio output,0x00200000,1,1,ksproxy.ax,6.01.7601.17514
Realtek HDA SPDIF Optical Out,0x00200000,1,1,ksproxy.ax,6.01.7601.17514
Realtek HDA SPDIF Out,0x00200000,1,1,ksproxy.ax,6.01.7601.17514


Audio Renderers:
Realtek Digital Output(Optical),0x00200000,1,0,quartz.dll,6.06.7601.17514
CyberLink Audio Renderer (PLAYMV),0x00200000,1,0,cladr.ax,7.00.0000.2111
Default DirectSound Device,0x00800000,1,0,quartz.dll,6.06.7601.17514
Default WaveOut Device,0x00200000,1,0,quartz.dll,6.06.7601.17514
DirectSound: Realtek Digital Output (Realtek High Definition Audio),0x00200000,1,0,quartz.dll,6.06.7601.17514
DirectSound: Realtek Digital Output(Optical) (Realtek High Definition Audio),0x00200000,1,0,quartz.dll,6.06.7601.17514
Realtek Digital Output (Realtek,0x00200000,1,0,quartz.dll,6.06.7601.17514

---------------
EVR Power Information
---------------
Current Setting: {5C67A112-A4C9-483F-B4A7-1D473BECAFDC} (Quality)
  Quality Flags: 2576
    Enabled:
    Force throttling
    Allow half deinterlace
    Allow scaling
    Decode Power Usage: 100
  Balanced Flags: 1424
    Enabled:
    Force throttling
    Allow batching
    Force half deinterlace
    Force scaling
    Decode Power Usage: 50
  PowerFlags: 1424
    Enabled:
    Force throttling
    Allow batching
    Force half deinterlace
    Force scaling
    Decode Power Usage: 0