Why is it that I can do chmod on my files when they are on my laptops hard drive, but when i make files on my external drive, i can't change their access rights.
I do:
chmod 755 somefile,
and on my local drive, the rights change accordingly,
but the very same command does nothing on my external drive.
How comes?

mount? Consider changing the filesystem if you only use the drive with Linux. – jippie Aug 8 '12 at 19:16