Please try restoring a previous snapshot to see if that helps the situation any.
To restore Fences to a previous snapshot:
-Right click on the desktop and select "Configure Fences..."
-Click on "Layout and snapping" on the left hand side of the configuration window that appears.
-Select a snapshot you wish to revert to. A preview window will appear showing you what the desktop will look like.
-Click Restore Snapshot to revert the desktop to this preview.