SymptomsWebDAV stops working on x64 machines after Plesk installation.
CauseThe reason of the problem is that Plesk is 32-bit software and when it is installed on the server (VE) it switches IIS to 32-bit mode. However WebDAV by default works in 64-bit mode and is not allowed by IIS Web Extensions.
ResolutionTo make it allowed please execute the following command:
IIsExt /AddFile %systemroot%\syswow64\inetsrv\httpext.dll 1 WEBDAV32 1 "WebDAV (32-bit)"