Note that this question is mostly so others can find this information.

I ran into a problem recently with my Fedora-14 virtual machine running on a Windows-7 host with VirtualBox.

VirtualBox could not start the Fedora virtual machine, but it could start a Ubuntu virtual server machine that was configured for 512 MB of RAM. The Fedora-14 machine was configured for 2 GB of RAM.

The Fedora-14 machine had been working a week ago. What had I recently changed...?

Answer to follow.

2 Answers 2


I had recently changed the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\LanmanServer\Parameters\Size registry key to 3. I did this to stop errors happening when I transferred virtual machine images over gigabit Ethernet.

This parameter allocates more system memory to the Server service which handles serving file-sharing connections.

The 3 value is for best file-sharing service. The default value for Windows-7 is 1. Setting this parameter to 2 instead of 3 solved my problem with VirtualBox not being able to get 2 GB of RAM for the Fedora-14 machine.


I had the issue generally described in the title (but varied in details). After a first install on a Windows 7 host and a successful run of Ubuntu VM, the application could not be started again. An attempt to start would show that a process is running in the task manager but no GUI appears.

Solution that worked for me: Start VirtualBox as Administrator.

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