Vaio VGN-FW21E intermittent sound problem?

[thohalle5]

I've had this problem for a while now and it's really starting to annoy me, sometimes when I turn on my laptop the sound doesn't work. Its intermittent and its doing my head in, does anyone know what is the reason behind this?

[mrstaku]

Vaio VGN-FW21L permanent sound problem

I have this problem too no sound in Win Vista enviroment nor after fresh install of win7 ultimate x64

have updated drivers tried MS drivers also Realtec ones still no joy so changed USB/sound card with the cable still the same in the control panel sound/properties it shows green bars moving also when pess test it showing as well but no sound and nor audio jack nor mic internal and external via mic jack works

only sound it makes when connected to any device via HDMI cable and only sound it makes the test sound in playback/properties but no sound when any media played (win media player ,VLC nor via adobe flash player) so would kindly ask anyone what would the blame  assume system board but may be wrong as do not want to spend £100+ on the system board and find out that something else failing

also may worth to mention when plug external USB sound card it works including microphone

any help will be greatly appreciated