failure to determine file ownership

I am running Vista Ultimate on a Packard Bell Easy Note with 2 Gb memory and

dual core processor.

I have a problem with a file I copied to my desktop.

It was a video file created with my mobile phone and was amongst a lot of

files on the storage card which I made a copy of whilst installing a bigger

SD card in my phone.

I was able to copy from the original sd card to the desktop and then from

the desktop to the new bigger sd card without problem but when I tried to

delete the copy on my desktop it kept telling me I did not have permission.

I eliminated all the files and folders one by one until there was only the

one video file left.

When I looked into the security on the file vista said it could not

determine ownership of the file and would not let me assume ownership.

I tried all the usual tricks of running windows explorer as an administrator

and tried to assume ownership of the file as instructed in the help section

buit would not let me do anything with it.

I cannot move it or rename it nor can I move or rename the folder structure

it is in.

Does anyone have any ideas on how to delete such a file?

I now have a folder on my desk top with sub folders all of which are empty

except for this one file several folder layers down and I can't do anything

with it.

Pease help if you can otherwise it is going to drive me round the bend.