Attempting to perform the InitializeDefaultDrives operation on the 'FileSystem' provider failed.

Here are the symptoms:

1.      Cannot find C and D etc. drives in windows/file explorer
2.      Unable to disconnect the mapped drive (etc K drive) – error message is “This network connection does not exist”
3.      Net use command does not list this drive
4.      Noticed group policy configured for both machine and user to map this drive during startup and login respectively
5.      A script was also placed in C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup to configure the mapped drive at startup

Actions taken:

6.      1. Disabled group policy stated in #3 above

7.      2. Removed the script from startup folder in #4 above
   3. Rebooted and issue was fixed
   4. Placed the script back on startup folder and rebooted again which did not re-produce the error.
   5. Furthermore, HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\ Explorer   Value: NoDrives was set to 0 to show all drives.