Sound problem with Win 7 default system sounds and internet audio

Upgraded Vista HP 32 bit to Win 7 HP 32 bit on Toshiba laptop Satellite Pro L300. All music and video stored on laptop play fine however Windows 7 default system sounds (or any other sound scheme listed) do not work and no sound on any internet site using either IE, Firefox or Opera. Have rerun install disk run diagnostics and updated drivers from drivermax without success. The sound device is Realtek High Definition Audio which appears and tests ok.

Any suggestions appreciated. I am new to this so please excuse me if i have not included anything you consider relevant.

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