Testbuild 4.3.21b97963 fails to start any guest

[andreas81]

I've also tested 4.3.18 and 4.3.20 - same problems here. Unfortunately I'm sure that this configuration has worked before - and I don't know what has changed (windows updates?).

I just encounter the following error message - before a dialog stating a timeout appears (see attached screenshot).

" Für die virtuelle Maschine Windows 8.1 (64-bit) konnte keine neue Sitzung eröffnet werden.

The virtual machine 'Windows 8.1 (64-bit)' has terminated unexpectedly during startup with exit code 1 (0x1). More details may be available in 'D:\Windows 8.1 (64-bit)\Logs\VBoxStartup.log'.

Fehlercode:E_FAIL (0x80004005) Komponente:Machine Interface:IMachine {480cf695-2d8d-4256-9c7c-cce4184fa048} "

For more details please take a look at the log files and please let me knwo if I missed some important piece of information or if there is something other I could contribute in order to help you to solve this problem.

Thanks in advance for your assistance.

[andreas81]

This might be related to KB3004394 (​https://answers.microsoft.com/en-us/windows/forum/windows_7-windows_update/windows-update-kb3004394-issues/ace25277-7f65-4486-bc44-c1b106907a18). This patch was installed on my machine - but was removed via ​http://support2.microsoft.com/kb/3024777. But the problem persists :-(

[andreas81]

Yes, I was able to workaround this issue by going to Programs and Features, selecting "Change" on SEP and set Proactive Threat Protection -> Application and Device control to "Entire Feature will be unavailable". If this is definitely a SEP problem please close this issue - if it is related to VirtualBox I hope it will be resolved in some future versions.