Fogssy wrote:memory is full (I downloaded a lot of files yesterday)
If this is the case, and the Virtualbox guest window is open and stable, then the problem is quite likely inside the Ubuntu guest OS, and you'd have to web-search how to access an Ubuntu OS when the disk is full, or how to access Ubuntu's version of Safe Mode, or a command line.
Post a log so we can double-check the Virtualbox setup.
Start the guest from full normal shutdown, not save-state. Run until you see the problem happen, then shut down the guest from within the guest OS if possible. If not possible, close the Virtualbox window for the guest with the Power Off option set.
Right-click the guest in the main Virtualbox window's guest list, choose Show Log. Save the far left tab's log, zip it, and post the zip file, using the forum's Upload Attachment tab.
