[CentOS] Centos 5.7--desktop icons are now a blank sheet of paper with the .desktop filename and they don't work

Just rebooted my box (switched keyboards, and since it's a PS/2 keyboard,
it needs to be done at poweroff) and when it came back up, (almost) all
the desktop icons I've created (as distinct from the ones that came with
the system) now don't display correctly.

Instead of the graphic assigned to each, it's just a picture of a blank
sheet of paper with the corner folded over, and the icon text is the
name of the .desktop file that defines the particular item.

worse, when I click one, they don't work... I get a popup window containing
this text (when attempting to fire up a local rebuild of Audacity, or
the appropriate name when attempting to use one of the other ones):

	The filename "Audacity (local build).desktop" indicates that
	this file is of type "desktop document". The contents of the
	file indicate that the file is of type "desktop configuration
	file". If you open this file, the file might present a security
	risk to your system.

	Do not open the file unless you created the file yourself, or
	received the file from a trusted source. To open the file, rename
	the file to the correct extension for "desktop configuration
	file", then open the file normally. Alternatively, use the Open
	With menu to choose a specific application for the file.

I don't really know what settings could have changed, but the ownership
and permissions look reasonable to me: the files in my ~/Desktop folder
look like this:

$ ls -l
total 88
-rw-rw-r-- 1 fredex fredex  305 Jul  9 16:15 Audacity (local build).desktop
-rw-r--r-- 1 fredex fredex  859 May 22 16:24 bar-008d741c23.desktop
-rw-rw-r-- 1 fredex fredex  376 Nov 11 09:16 Firefox-4.desktop
-rw-rw-r-- 1 fredex fredex  311 Nov 10 14:00 fred's desktop on cibf-fred1pc.desktop
-rw-r--r-- 1 fredex fredex  442 May 27 19:53 gegl-00efc0b78f.desktop
-rw-r--r-- 1 fredex fredex  981 Oct 30  2009 greasy-00f830171b.desktop
-rw-rw-r-- 1 fredex fredex  288 Jun 25  2010 Osmos.desktop
-rw-rw-r-- 1 fredex fredex  369 Jul 10 23:14 Pysol-FC.desktop
-rw-rw-r-- 1 fredex fredex  378 Feb 22  2011 quadra.desktop
drwxrwxr-x 2 fredex fredex 4096 Jan 27  2011 radio stations
-rw-rw-r-- 1 fredex fredex  359 May 24 21:14 razorsql.desktop

and the Desktop folder's permissions are:

$ ls -ld Desktop
drwxr-xr-x 3 fredex fredex 4096 Oct 25 15:03 Desktop

note that the Desktop folder contains a subdirectory named "radio stations",
and that its representation on the desktop looks correct. but when I click
on it to open up that folder, all its contents are also broken in the
same way.

Anybody got any clues?

-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
                        The Lord is like a strong tower. 
             Those who do what is right can run to him for safety.
--------------------------- Proverbs 18:10 (niv) -----------------------------