Why is my virtual machine inaccessible?

I want to start my virtual machine but in VirtualBox Manager, it says it's inaccessible and that I should be inspecting the error log which says:

Document is empty.
Location: '/home/ron/VirtualBox VMs/Semios Win7 /Semios Win7 .vbox', line 1 (0), column 1.
/home/vbox/vbox-5.0.12/src/VBox/Main/src-server/MachineImpl.cpp[740] (nsresult Machine::i_registeredInit()).
Result Code: 
NS_ERROR_FAILURE (0x80004005)
Component: 
MachineWrap
Interface: 
IMachine {f30138d4-e5ea-4b3a-8858-a059de4c93fd}

The only problem is, I don't know how to interpret what I'm seeing. What does all this mean?

Solution 1:

Go to the location where you store your VM /home/ron/VirtualBox VMs/Semios Win7 /.

Open .vbox in your favorite text editor to check if it is empty. Probably it is :) In the same folder you should have file Semios Win7 .vbox-prev. Copy the contents of this file to Semios Win7.vbox, save, and try again.

Now it should work. I did the same and it worked for me.