help! Could not open medium - VERR_RESOURCE_BUSY

[virtualboxerman]

When I try to start my Windows 7 Bootcamp machine, I get the below problem.
I haven't used VirtualBox for a while, so I'm not sure if I was having this problem before upgrading my OS, but I'm using Mountain Lion.
I know in the past it worked fine. I have just updated to the latest virtualbox version and installed the Extension pack, and no dice.
Any ideas how to fix this? Thanks!

Failed to open a session for the virtual machine Bootcamp.

Could not open the medium '/Users/xxxxxxx/VirtualBox VMs/Bootcamp/win7raw.vmdk'.

VD: error VERR_RESOURCE_BUSY opening image file '/Users/xxxxxxx/VirtualBox VMs/Bootcamp/win7raw.vmdk' (VERR_RESOURCE_BUSY).

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: Medium
Interface: IMedium {29989373-b111-4654-8493-2e1176cba890}

[ChipMcK]

I haven't used VirtualBox for a while, , , , but I'm using Mountain Lion.

Do you recal what OS X version you last ran "fine"?
If it was before Lion, then OS X reorganized your internal hard drive partitions and Boot Camp is now number four, not three.
You need to recreate the raw vmdk file.

[virtualboxerman]

I believe it was Lion, not Snow Leopard when I was able to run it without a problem.
Sorry I don't know much about these things..what steps do I take to check if Boot Camp is number 3 or 4 or how to recreate the vmdk file?

[ChipMcK]

Sorry I don't know much about these things. . . . how to recreate the vmdk file?

Hmm, recreating in raw file is rather technical, geeky.

what steps do I take to check if Boot Camp is number 3 or 4

Disk Utility, located in /Applications/Utilities folder will tell you which partition it is.
After launching DiskUtil, select BootCamp from list of partitios on the left, then press the infomation (the big blue "i") at the top.
The new pane/window/panel will list the number as Disk Identifier disk0s4 , where the number 4 is the partition number.
That is nice info is verify.

The question is if that is what is reflected in the raw file.

Perhaps, someone with knowledge of raw files can assist further

Edited to correct typo's