I have a configuration specific custom property called "Part Number" set equal to \$PRP:"Number"\$PRP:"SW-Configuration Name".  It makes "Part Number" the same as "Number", but with the configuration name tacked onto the end.  Every time I enter the above string it looks ok at first and the evaluated value is as expected.  However, once I close the custom properties dialog and open it again all the quotes (") have been removed, causing the property links to not function.