My computer got so slow that the mouse was slow and jerky and I had to reboot. System interrupts was at about 30% CPU time. My PC is now with 5 days uptime and the bug seems to have disappeared. The following solution seems to solve the issue :

• 1. Right-click on the speaker icon
• 2. Select playback devices
• 3. Click on the speaker properties
• 4. Go to the enhancements Tab
• 5. Click Disable All Sound Effects
• 6. Click OK. You're done!

The sound enhancements seem for some reason to cause the problem even when not used. So disable them following the procedure above. Good luck!