Podes tentar converter de FAT para NTFS. Nunca experimentei com um disco externo, mas deve funcionar na mesma. Onde está «c:» tens de por a letra do disco:
1. First, back up your data. The conversion process almost always works flawlessly, but there is no point in taking the risk.
2. Click the <Start> button.
3. Click <Run>.
4. Enter "cmd" into the text field labeled "Open".
5. Click the <OK> button.
6. Enter the command "vol c:" to find the volume label for the C: partition.
7. Enter the command "convert c: /fs:ntfs" to convert the C: partition from FAT32 to NTFS.
8. When prompted, enter the volume label for the partition.