In a post below you will see that I was in the process of burning Blu-Rays for backup as I thought one of the (relatively new) hard drives was on the way out. I had a thought that it might be something else so I changed the connection to the HDD dock from e-SATA to USB2.0 – and it ran with no problems! I had bought an e-SATA II adapter that fits in a PCIe slot in the main computer to drive the HDD dock (for speed of data transfer). Unfortunately the only vacant slot was sandwiched between the two (high power) graphics cards – which run very hot. I was a bit bothered about doing this, but having no choice I fitted the card and ran the HDD dock – up until recently. Looks like the graphics cards finally cooked the little SATA II card and this led to the problem. Annoying, but the USB2.0 port seems plenty fast enough for my backup storage application, so I needn’t have gone down the SATA II route at all.