Reading file after written to NTFS problems

By right clicking the WindowsXP hard drive icon on the live distro KNOPPIX 5.0.1 , I can write to any NTFS partition (create a .doc from Open Office and copy it to the NTFS drive). The problem arises when I enter the Windows partition (after unmounting Knoppix). I see the file but lack permissions to read it.
If a .doc file already exists on the NTFS partition I can modify it and then read it when Knoppix is unmounted but cannot create a new .doc file to read via Open Office.
Can anyone explain this to me?

It's a little gift from Microsoft. The conventional wisdom is never to write to a NTFS partition with Linux. Some people think that maybe those working on the NTFS file system in Linux will eventually crack the barriers that MS is putting in the way, others including myself suspect a more deliberate effort is going on to keep this from working and suspect that the automatic "security updates" are being used to make sure that the NTFS system can't be written to safely by Linux on a continuing basis. In the past writing to an NTFS partition has been known to completely corrupt it, sometimes right away, sometimes in such a way that the corruption isn't immidately evident. If you're brave enough to try writing to your NTFS partitions with Knoppix then good luck to you, but it will be a long time if ever before I trust it enough to do it.