Black Screen after upgrade to 4.1.4, Win7 guest

[unit0x03]

Hey all,

Just upgraded to 4.1.4, and now my Win7 guest just gets a black screen on login. If I boot into safe mode and uninstall the virtualbox guest additions, then it goes back to normal, but of course I lose all the guest additions. Reinstalling the guest additions doesn't help, it just goes to a back screen before login.

Anyone else seeing this behaviour or have any suggestions on how to fix it?

[unit0x03]

Got it sorted, but only by installing the experimental D3D support. (ie: boot to safe mode, tell it to install D3D, say "no" at the prompt to install basic D3D)

It's possible that an old install of the experimental D3D support stayed present, and then wasn't getting uninstalled when upgrading.

[Perryg]

Yes and may cause you issues again. The best way is to remove the guest additions in safe mode if you installed the d3d drivers while in safe mode.
Then install the new wddm drivers. Note you do NOT need to be in safe mode to install the wddm drivers.

[PhobosK]

Yes and may cause you issues again. The best way is to remove the guest additions in safe mode if you installed the d3d drivers while in safe mode......

I have the same problem but the bad thing is that my Win7 Guest OS behaves the same way in safe mode (i.e. loading the VBoxGuest drivers and leaves the screen blank though the mouse cursor works).
I tried downgrading to the older version+extension pack but it did not help either....
Disabling the 2d and 3d acceleration in the settings of the guest os doesn't help either...

So i am stuck at the blank login screen of win7. How can i remove the already installed (in safe mode) win drivers of Virtual Box? Or is there any other way to make win7 bypass the drivers when choosing the "Safe mode" start after a crash?