Did this VM has a RDM attached to it and then removed ? If you removed the RDM, and did not select "Delete from Disk", the pointer files for that RDM would still be in the VM directory, causing ESX to try to reconnect to it and failing, giving you this error messages.
You can go into the VM directory on the datastore, and browse through the list of files. You will see the 2 files, 1 with *-rdm.vmdk file, and another *.vmdk file. You can remove these 2 pointer files to eliminate the warning messages.