VBOX OpenSuse Guest Will No Longer Boot

I have/had a working OpenSuse(13.1) VBOX(4.3.8) guest running in a 32-bit Windows 7 host. It will not longer boot.


I had been cloning it successfully, and using the clone as my working machine and keeping the original as a backup.


Today, I shut down the working machine and made a clone as usual.


Neither the clone nor the working machine would start completely. They showed the exact same symptoms, so it appears the problem occurred in the working machine during shutdown.


A previous clone, from two weeks ago boots up without issues.


The symptoms seem related to the display. During bootup, we eventually see a black/green chameleon desktop, but then the display enlarges and goes black. An "X" cursor appears, and that is it.. That is were the bootup process hangs. In a normal bootup process, after the chameleon desktop appears, the next viewable step would be for hardrive icons and others to up near the center of the screen. This does not happen.


I have tried changing the display settings (from two displays to one, and video memory allocation, but that does not help.)


Any idea what is causing this, how to troubleshoot it and how to fix it?


Thanks