Cannot open SU file

I saved a file on my desktop. When I try to open it I get the following message and cannot open it.
Any way to overcome this problem?
Thank you.

Try logging into SketchUp as an administrator if you have not done so previously. If that does not solve the issue, try to open the back up (.skb) file. You will need to change .skb to .skp and it is advisable to copy the file using a different filename as well.