In spanish the % sign is supposed to be separated from the number [1 and 2 both in spanish] so I separated the %% that draw the percentage sign from the number.
[1] http://www.fundeu.es/recomendacion/el-se-escribe-separado-de-la-cifra-a-la-que-acompana-802/
[2] http://aplica.rae.es/orweb/cgi-bin/v.cgi?i=QGkHLBzKcEgZrQyD
PD: I know that probably this is not the propper place but I don't know where submit the fix or if I do it right
#, c-format
msgid "Checking in progress on %d disk (%3.1f%% complete)"
msgid_plural "Checking in progress on %d disks (%3.1f%% complete)"
-msgstr[0] "Comprobando progreso en %d disco (%3.1f%% completado)"
-msgstr[1] "Comprobando progreso en %d discos (%3.1f%% completado)"
+msgstr[0] "Comprobando progreso en %d disco (%3.1f %% completado)"
+msgstr[1] "Comprobando progreso en %d discos (%3.1f %% completado)"