Virtualbox Windows 7 guest OS inaccessible after upgrade to 4.0.8

I upgraded Virtualbox to v4.0.8. The Windows 7 Guest OS booted up and shut down with no problems. The second time I tried to boot, I got the following error in the main Virtualbox window, and it said the OS was inaccessible:

Location: '/home/user/.VirtualBox/Machines/W7/W7.vbox', line 142 (3), column 36.
/home/vbox/vbox-4.0.8/src/VBox/Main/src-server/MachineImpl.cpp[679] (nsresult Machine::registeredInit()).
Result Code:
NS_ERROR_FAILURE (0x80004005)
Component:
VirtualBox
Interface:
IVirtualBox {d2de270c-1d4b-4c9e-843f-bbb9b47269ff}

This ticket solve the issue: http://www.virtualbox.org/ticket/8948

I had to edit the .vbox file to remove a "strange" character at the line specified above and once back in the Guest OS, edit the registry to fix the issue.

1. Go to HKLM\SOFTWARE\Oracle\VirtualBox Guest Additions
2. Create a string key VersionEx (use exactly this spelling)
3. Give it a reasonable value
4. Shut down the VM.