Oracle VM not working anymore

[guster000]

Good morning /evening.

I searched all over Internet and i couldn't find a suitable solution for my problem.
I 'll try to be the most explicit as I can.

So, I was using Oracle VM 4.3.6 with a Windows 7 Professional x64 and everything
were fine.I had three guest : Windows 7 x86 (for development purpose), Ubuntu 13.04 and Ubuntu 14.04.1 LTS (testing before switching from previous version).
The first two were working well enough, but with the third, I couldn't change the resolution of the Ubuntu 14.04.1's
Desktop. After some research, I found out it I had to upgrade to a recent version of Oracle VM, what I did by downloading and installing
the 4.3.20 version.

That's where the problems appeared. Everytime I launched a VM from Oracle main window, it would show a tiny
window in the top left corner with barely visible content. I could resize it, but switching to Fullscreen or Scaled
mode with Right Ctrl + F || C would crash the machine or just make it disappear. After few trials, I thought the VMs themselves
were faulty, so I delete them and tried to reinstall, but it didn't ever start.Also installed the 4.3.6 that was working first,
but even this version was bugging.

Then I reinstalled the entire host system with Win 7 Ultimate x64, and tried to install the Oracle VM 4.3.20, 4.3.22 and even the latest
test build as I speak but the same problem occur over and over.

Please help me find out what's wrong with my system, I kinda need a VM to sandbox many softwares as fast I as can.

Thank you fr reading, hope I'll get some answer.

[scottgus1]

Any version from 4.3.14 onward has been affected by the developers' ongoing efforts to plug a security hole. See the security sticky at the top of the Windows Hosts forum. try the latest build to see if the problem persists, or try 4.3.12 to get the last version without the security-patching. (Note, keep malware off you host and you should be safe from the security hole.)