Windows 8.1 - LaCie Quadra External Drive no longer recognized.

I am running one of these...

https://www.lacie.com/ie/support/support_manifest.htm?id=10313

...onto my DELL desktop via USB 2.0

The LaCie is exactly one year old and I don't use it very often. It is only switched on when I have new image files to copy across.

Yesterday, I switched it on and nothing happened.

I tried another USB port and, eventually, it sprang into life. I copied across the files.

Today, I checked it again and I got an error message (accompanied by a warning sound) saying that "The last USB device you connected to your computer was not recognized and may not be working correctly."

I tried other USB ports and it's the same with all of them now.

I haven't had the chance to try another cable yet.

In the meantime, is there anything else I could be checking?

As I say, I don't use it that often. So, could something in a recent Windows update be affecting it?

How would I check for the drivers that run the LaCie? Where would they be located on the computer? Could they be the problem?

Many thanks.

D.