Help, New download, app doesn't start

[jobber]

I downloaded the latest stable version 4.3.9 for Windows 10.
I have tried both the 32 and 64 bit version.
Downloaded and installed the app without any problems, but when I try to run it, I get nothing. No app opens.
When I look in the TaskManager/Details tab, when I try to start the qBit app, I see it appear for like 1 second, then it disappears.
I have tried rebooting my PC, in case that was needed as part of the install, but still nothing. I have no other torrent apps running.

Is there some kind of problem with version 4.3.9? How come I can't run qBit app after finishing the installation?

[Peter]

What kind of anti-virus software are you using?