Thanks I'll try that but POI loader also shows the SD card. However in doing various things I found that my new POI file was now showing twice in the list of Custom POIs. So I deleted the one on the SD card but that didn't solve it so I then tried formatting the card (8Gb by the way) and that's when my problems started. The unit now won't recognise the card or says it needs formatting but it won't format. So a bit stuck at the moment.
Try taking the sd card out and formatting it as FAT32 on a laptop \ pc then formatting it again on the sat nav.