Can't start guest machines after Update to 5.1.2

[Deusexmachina]

Dear community,

since the recent update to version 5.1.2 my Linux guest (Linux Mint Xfce 17.3 32bit) doesn't start any more. Instead there is an error (see picture in attachment).

The Host ist Windows 7 Professional with all updates and service packs. Antivirus ist "Kaspersky Antivirus".
The log file and the hardening log file are attached.

I'm afraid I can't attach the hardeninglog, because it's too big (346kb).

I hope you can help me. It's rather annoying.

regards,
Deusexmachina