System is Windows 7 Pro 64bit.
In windows explorer, select a xxx.asc file (encrypted by gpg4win).
If Kleopatra is NOT started, clicking on one of the context menu items e.g. "Decrypt and verify" results in the error message "Can not connect to the GnuPG user interface: General error"
If Kleopatra IS started, clicking on the context menu item works.
That means, the explorer context menu items do not start Kleopatra.
Double-click on the xxx.asc file does start Kleopatra and successfully starts the decryption process.