First of all, I want to thank everyone for the great advice on this site. I have learned a great deal. I have a WD 400gb external hard drive connected to my Compaq system. It has a Pentium 4, 3.07 ghz and 512 ram. Every time I try to back up a movie or transfer a movie folder into it, it locks up the computer. The hard drive has nothing on it and has been formatted. My other hard drives, internal and ex. do not give me this problem when doing the same thing. Any suggestions? Thanks.