When I copy files from my desktop at home to my external (portable) backup hard drive, the files are listed on the portable drive in Windows 7 Explorer. However, when I get to my office to copy the files, they are no longer listed on the portable drive. This happens frequently even after painstakenly checking at home that they are there. Any clue to what's going on?

Hi, PhilvK. Sounds like you don't have a copying problem; you have a reading problem on the office computer. What Windows version does the office computer use? What does Disk Management (on the office computer) say about that portable drive? Does it even know the drive is there? Do you have access to another computer that should be able to read the directory of that portable drive? You said it "happens frequently". Not "all the time"? Could there be a physical connection problem between the portable drive and your office computer? What kind of connection: USB? eSATA? Connected directly to the computer, or through a hub? Does the office connection supply enough power (through the USB cable) to spin the portable disk drive? RCR. C. White, CPA Microsoft Windows MVP

Whats the office computer operating system? May be no driver for that drive.

Hi, As I understand, the files are not listed in your external drive while connecting to the office computer. If it is the case, I would like to suggest you taking the following options: 1. Check the permissions of the external hard disk, make sure that the logged on user account has the Read/Write privilege. If not, please take ownership of this disk: 1)Click Start –> All Programs ->Accessories 2)Right-click Command Prompt and select Run as administrator. 3)Type: takeown /f filepath (Replace filepath with the location of your drive, example d:\) 4)Press Enter, you will be prompted with completed successfully message. 5)Type: icacls filepath /grant yourusername:f (Replace filepath with the location of your drive, and yourusername with your profile name) 6)Press Enter, you will be prompted with completed successfully message. 7)Then try to delete files in this drive and see if it works. 2. Boot in Safe Mode to see if the files are listed. 3. Run the following command to display the files: dir f: (f: is the drive letter of external hard disk) If there are multiple files displayed in the command prompt, you can use the copy command to copy the files for a test: Copy D:\test.txt F: Best Regards Dale