Hi TexJay,
I appreciate your observation for system security, if we can’t find a registry entry, it may be hidden.
Check this website below to discover Hidden Registry Keys in Windows.
http://nagareshwar.securityxploded.com/2010/01/30/discovering-hidden-registry-keys-in-windows/
In your current scenario, I suggest to execute a full scan in the safe mode to see the result.
For Windows 10,
please forcibly shutdown two or three times, and system would enter advanced recovery interface. Click advanced options to enter WinRE. In WinRE, click troubleshoot->advance options->startup settings, click Restart, then system would boot to safe
mode.
On the other hand, about wav files, they seemed were created by the third-part software, please recall carefully what you have installed or downloaded recently, maybe something started automatically during system
boot and created these wav files. Clean boot can be a suitable method, try it to test result.
Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Hope my clarification is clear.
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