I have spent all day solving how to get the Win7 guest to recognize my USB devices, and finally managed it, re-installed VirtualBox 5.0.16, re-installed Win7 into it from my CD, installed the Extension Packages and added myself to the Vbox users group..followed all the instructions to the letter, and was happily testing my favourite program in Virtual box, TMPGEnc, which wouldn't run because not enough memory, so I upped the base memory allocation to 1024 as required, and it worked. I was even able to encode a short video, just to prove to myself that I had finally managed to get VirtualBox working as guest on Ubuntu host. I only need it for a few programs. Then , I powered off the Virtual Box and when I went to start it again, there was no Win7, it had gone, and I was being asked to insert my disc to install a new machine all over again. What could have happened? is this normal? Is there any way out of this without yet again going through another Win7 install?