I have a Late 09 15" MBP and a WD 1TB external HD. I've never had a problem until now. I start up the hard drive, then it loads up fine and the Mac recognizes it just fine. As soon as I try to copy something - doesn't matter how big it is - I get an error and at the end it says "(Error code - 36)". It just says the file cannot be read or written. Weird thing is I can access everything on the hard drive. Anyone have any tips before I try reformatting the HD?