log into the DB and perform the following

SELECT vm_name frim vms where vm_guid = (SELECT vm_guid FROM
vm_images_view where imagestatus = 2);

See if you get the VM which the disk is locked on it.

If so do:
SELECT image_guid from vm_images_view where imagestatus=2;
# Get the guid returned and then
Update images SET imagestatus=1 where image_guid = {The guid which
returned in the last query}