How do I repair a corrupt VHD?

[Crummy]

I am trying to run a virtualbox guest from an existing Windows XP VHD. It had worked in the past but now it seems the VHD is corrupted. I am running VB version 4.3.6 r91406.

I will post an image of error box once I have been a member for a day and am allowed to. Sorry for the inconvenience.

Below are the "Details" text.
Failed to open the hard disk file path\to\vhd.
Could not open the medium 'path\to\vhd'.
Failed to open image "path\to\vhd" (VERR_SHARING_VIOLATION).
VD: error VERR_SHARING_VIOLATION repairing corrupted image file 'path\to\vhd' (VERR_SHARING_VIOLATION).
Result Code: E_FAIL (0x80004005)
Component: Medium
Interface: IMedium {05f2bbb6-a3a6-4fb9-9b49-6d0dda7142ac}
Callee: IVirtualBox {fafa4e17-1ee2-4905-a10e-fe7c18bf5554}
Callee RC: VBOX_E_OBJECT_NOT_FOUND (0x80BB0001)

I have already tried to re-size the drive by using VHD Resizer and also tried converting to a VDI but both time receive errors about not a valid VHD or VHD is corrupted/unreadable.