/etc/fstab file no longer working when writing on a NTFS disk My Macbook Pro runs 10.6.8 and I have a NTFS 500G disk.
In order to write into the disk, I had tried to edit the /etc/fstab file.
It did work for years, but recently, I found it do not work and I don't know why.

Can anyone tell me why it has stop working and how to fix it?

I know installing some softwares can solve this problem, but I prefer to know why the /etc/fstab file invalid now.
The NTFS driver (ntfs.kext) Apple supplies with OS X provides read-only access. You need to get a r/w driver, and your best bet is to get on by installing OSX FUSE (File Systems in User mode), from http://osxfuse.github.io/ and then the Tuxera NTFS driver (www.tuxera.com/products/tuxera-ntfs-for-mac/‎), or the freeware NTFS-3G. Get the freeware version, and it works just fine. That should solve your problem.