Hello, I just bought a Macbook Air, and I have WD external 1 TB that I purchased back in Feb 2011. I have had no problems writing files to the external harddrive in the past on my previous windows based laptop (asus), but now that I have a macbook air I can only pull files from the drivedrive and place them onto my mac, I can't write anything to the external harddrive from my mac. I believe this is called read only. Is there anyway that I can fix this issue without reformatting my WD harddrive?