That still sounds like a driver problem. Have you uninstalled the drivers and reinstalling them ? This just sounds too simple
I have a 20 month old Toshiba Satellite L755-S5356 with I5-2430M processor and Connexant sound. I'm having problems where speaker sound plays for 15 to 60 seconds then stops. I have Windows 7 Home Premium 64 bit OS and 8 GB RAM. It only happens with the laptop speakers. If I plug in earphones, they don't have the problem. If I pause playing a video, wait 30 seconds or so, then restart it, I get speaker sound again for a short period, but then it goes silent again while the video continues to play. This happens with Youtube downloads, Pandora web site, or audio CDs - it doesn't matter what the source of the sound is, it happens with everything, and is most annoying. Since it happens with music CDs, I've ruled out a buffering/bandwidth bottleneck. I have a 22 Mbps cable connection with wireless-N 5 bars connection FWIW. It happens with Windows Media Player, the latest Adobe (Shockwave) audio and flash player add-ons with IE10, Firefox 22, and Chrome.
In attempts to resolve the problem I've booted to Safe Mode and run Norton Security Suite full scan for virus and Malwarebytes scan, the Control Panel's sound troubleshooter, and the Toshiba PC Diagnostics tool and found nothing. I was going to restore to factory settings using the DVDs I burned when the laptop was new, but got an error, so I formatted the hard drive and reloaded Windows 7 Home Premium from scratch using an install DVD. I used the COA code from the sticker on the bottom of the laptop to activate Windows 7. I saved the TOSAPINS folder with the drivers and used that to reload all drivers, then installed all the hundreds of Windows 7 updates using Windows Update. I've gone to Device Manager and checked for driver updates, but it says I have the best and most current ones already. There're no ? or ! in any Device Manager entries. I even looked through the Windows system event logs but didn't see anything related. I downloaded the most current driver from Toshiba, but it failed to change the symptoms.
In researching this in the Toshiba sound forums, I see people with different Satellite models having the same problem. They all have the Conexant SmartAudio HD sound. I went to Conexant's web site to see if they might have a different driver that could help, but they want you to spend $30 for a product I never heard of that replaces ALL Conexant drivers. I have posted this in the Toshiba Sound forum, but so far all I've gotten was a suggestion to download the latest sound driver which I've tried 3 times with no success.
I also tried booting Ubuntu and Linux Mint, but neither has the driver for this sound chip.
All this but the problem persists. Can any kind soul suggest what I should do next? TIA