VirtualBox Unable to Run Two Instances

Double Bows by Nicholas_T

I have been using VirtualBox for awhile and have been pretty pleased with it considering it’s a free solution.  I blogged about wanting to try it over two years ago.

Today I started up Windows 7 on my iMac.  Then I tried to start up Windows XP but got this error.

Failed to open a session for the virtual machine Windows XP Pro Media Center.

PIIX3 cannot attach drive to the Secondary Master

Unknown error creating VM (VERR_SHARING_VIOLATION).

Fortunately Google came to the rescue and led me to this article in the VirtualBox forums, Can’t run multiple Instances on OSX Leapord.  Once I unmounted the DVD drive in Windows 7 (Devices –> CD/DVD Devices) I was able to start Windows XP.

The lesson is you can’t run two instances if both want to mount the same DVD drive. Not sure if this is a problem with Parallels or VMWare.

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