can't copy/backup to my external drives

Hi!

First I would kindly ask forum admins to transfer my topic to more suitable subfolder, I really don't know here to post my problem. Thanks.

Now to the problem. I have Asus N55SF laptop, with Windows 7 SP1 64 bit. Also, I have 2 external hard drives. One with USB 3.0, and one USB 2.0. Following problems, I am going to describe below, happen to the both of them. Just to mention, external drives are tested on desktop computer and following problems do not happen.

Let me now describe what happens when I try certain actions:
- When I try to copy large files (10 or more GB) I get an error that destination is no longer visible. External drives disappear from My Computer and I can't do safe remove. But when I copy files using programs FastCopy or TeraCopy everything copies well and drives do not disappear.
- When I try to do Windows Backup and encrypt them using BitLocker drives also disappear, and are not visible within OS.
- There is a difference between external hard with USB 3.0 port and the one with 2.0 port:
--- when one with 3.0 disappears after described actions I can't see it from Device Manager, I can see it only after windows reboot. USB 3.0 disk connects to one USB 3.0 port on laptop.
--- when one with 2.0 port disappears I can see it from Device Manager, and I only have to unplug it, and plug it in again to see it. USB 2.0 disk connects to 2 USB 2.0 ports on laptop.

Common to both disks is that when then disappear from My computer the diode on the external disk cases are still flashing, what probably means that they have some power. Both disk are formated to NTFS, and Allocation unit size is set to: Default. Their removal policy is set to: Better performance (default). On laptop I only have Windows, Office and Asus drivers. Antivirus is: MSE.

Thanks for replies

Hi!

thanks for the advice, but I did turn usb suspending already, and it did not help. I have also deactivated "Allow windows to turn this device off" under Power Management of USB root hubs in device manger. Did not help.

I'm not an expert in anything! :)

I think it could also be a BIOS issue, a driver issue, or a USB Controller issue. You might see if the suggestions in this Microsoft forum thread by Vivian Xing are helpful. Don't be alarmed that the original poster was talking about his graphics card and a 250GB external hard drive. These are merely diagnostic steps that can be used for other problems.

HELP!! EVGA Geforce 8400GS PCI and Toshiba 250 GB external hard drive (USB)!!

Try using a powered USB hub.