update: it appears the Emsisoft anti-malware latest update has blocked QB. I set the app to "trusted" in Emsisoft, and it is still being blocked with no notification. I have filed a support request with Emsisoft.
Win 10 64.
Suddenly latest version 4.3.7 refuses to show the QB main window when launched. No error occurs.
I restarted Windows; same behavior. I uninstalled QB, then rebooted, amd re-installed: same problem.
QB is not starting with Win 64, and I set that option when i reinstalled.
I notice that Task Manager shows two QT processes running; both labeled 32 bit.
I re-installed the latest version, and it started to launch, but, then the main window closed, and further attempts to start the app do nothing.
I uninstalled the release version, and installed the current beta 64: same behavior.
No other software exhibits this behavior.
thanks, Bill