At the beginning of August VMware has released Update 1b of vCenter Server 5.1.
This release aims to fix a number of bugs, among which the most relevant is related to the cancellation of virtual machines using the Datastore Browser:
All virtual machine folders on a VMFS volume are deleted after a single virtual machine folder is attempted for delete resulting in failure, and you choose Delete again by using the Datastore Browser
When you attempt to delete a virtual machine folder while the virtual machine is powered on, a message similar toCannot delete file. [VMFS] <virtual_Machine_Name> is displayed. If you click the Delete button again without closing the datastore browser or changing the selection, and attempt to delete the same virtual machine folder that failed to delete earlier, all virtual machine folders on the VMFS volume might now get deleted.
The complete list of these fixes can be found in the release notes.