I am also having this issue. Windows 11 Build 2261.ni_release.220506-1250. Windows Defender is the only anti-malware on the system.
Upgrading over Fences 3. I have not yet tried the purge batch file.
Fences 3 does not appear in my Programs and Features and running the \Program Files (x86)\Stardock\Fences\uninstall.exe produces the error "Invalid start mode: archive filename"
I downloaded the Fences 5 installer from the purchase page at Stardock.com.
Fences 3 says there is an update available. I downloaded and tried to install that, and got the same error "Could not open the uninstall executable for writing: Encountered a sharing violation while accessing C:\Program Files (x86)\Stardock\Fences\lua5.1.dll. C:\Program Files (x86)\Stardock\Fences\uninstall.exe"