Thanks for the response.
Answering your questions MArk:
"but this External HDD is a DISK drive in a case, not a USB stick, right? "
It is a 1tb Hitachi External Hard Drive exactly like this one: http://www.touropro.com/en/product/tour ... index.html
"What filesystem is in place on the external disk? Is it Window-based (NTFS)? Or, is it Linux-based (Ext4)?"
I use it as a storage disk only , no operating system.
When I say that I tried it on another PC it was a computer with the latest Linux Mint XFCE version OS installed.
Well I hope that helps, but I continued to try other things and discovered that after reinstalling the Linux Mint os it actually recognized the hard drive and works perfectly, but only when i connected the short USB cable that comes with the drive.
If I connect the HDD through a USB hub or even a single USB extension cable the HDD is not recognized.
With my limited PC knowledge I guess the problem is the voltage going to the HDD, may be it is not enough.
I believe that the USB 3 HDD need 5v to work perfectly. maybe it is not recieving this when connected to a HUB opr long lead, some kind of resistance in the cable? not sure?
If I am correct would changing the power supply help or should I get a USB HUB with it own transformer connected or some sort of docking type station for the HDD, if they make them?
Can some give me a response, thansk