Verbiage change. Bug 185536, patch by kairo@kairo.at (Robert Kaiser),

r=gisburn, sr=bzbarsky

layout/html/base/src/printing.properties

@@ -69,7 +69,7 @@ NS_ERROR_OUT_OF_MEMORY=There was a problem printing. There is not enough free me
 NS_ERROR_NOT_IMPLEMENTED=Some printing functionality is not implemented yet.
 NS_ERROR_NOT_AVAILABLE=Not available
 NS_ERROR_ABORT=The print job was aborted, or canceled.
-NS_ERROR_FAILURE=Printing failed for some reason.
+NS_ERROR_FAILURE=An unknown error occurred while printing.
 NS_ERROR_GFX_PRINTER_STARTDOC=Printing failed when starting the document.
 NS_ERROR_GFX_PRINTER_ENDDOC=Printing failed when completing the document.
 NS_ERROR_GFX_PRINTER_STARTPAGE=Printing failed when starting the page.