Audio performance and crash in Vista

About a week ago my Toshiba Protege began suffering serious problems which
seem to relate to audio/video and the RealTex HD Audio card (Vista 32 bit).
Typically after 5 to 30 minutes of playing an audio stream the CPU usage goes
to 100%, the audio becomes distorted. Now today my computer simply freezes
while this occurs and after about 5 minutes it shuts down. There is no
ability to switch program or bring up Task Manager (other than the tray
icon.) At restart no problems are reported. Vista seems to think everything
is hunky dory as long as I don't start streaming audio (or earlier playing
DivX files).

The behavior of audiodg.exe was similar to earlier reported problems but
turning off enhancements did not solve my problems. I re-installed the
original Realtek drivers and continued to have problems. Then I installed
the recently updated RealTek driver (6.0.1.5657). That seemd to eliminate
the sluggishness but after an hour or so of streaming CPU usage went to 100%
again and shutdown occurred.

These problems never occurred in the past. I've uninstalled DivX and Real
player but the error occus in Windows Media 11 as well.

It appears that I should have taken the advice of installing XP with the
disks given to me at time of purchase. But now I've purchased updated
software for Vista. So all those wonderful promises of productivity gains and
improve experience are wasted by one week of frustration (thanks once again
Microsoft).

(Symantec and Windows Defender are updated. Computer has been scanned by
both. Disk Defragmentation and disk check have been done.)