Support the following scenario that may cause the described behavior.
- Double-click on the downloaded installer file.
the tiny loader downloads the Qt online installer wizard.
- While the tiny loader is in progress double-click on the installer file again.
the second loader may hang.
show a message box with title:
Unipro UGENE Installer Is Already Started
Unipro UGENE Online Installer is already started, see progress of the loading in another window.
This scenario should currently work on Windows only. Note that on Linux several installers are currently run, but all installers finish successfully :-D, there is no such problem on macOS as there is another type of installation.