Help with error code -43 on 2009 MacBook Pro 13'

Hello -

Looking for some help with error code -43 on my 2009 MacBook Pro 13".

Running ElCapitan (unable to update to High Sierra with this machine).

I have a couple files on my desktop, created today --- ex. 1 is a screen shot, 1 is a Keynote presentation >>> trying to delete these, and if I either attempt to drag them to the Trash bin, or right click and choose Send to Trash - I get the following error:

"The operation can't be completed because one or more required items can't be round. (Error code -43)"

Any help appreciated.

Tks!