DH67CF and USB3 Problems

I have just put together a nice little PC based on the DH67CF - nothing fancy, just straightforward - see below. Everything is working as it should except for the external USB 3 ports. I have a Western Digital My Passport USB3 external disc on which I store my data, music etc. Essentially, the USB3 ports 'freeze' during use and stop working. Once this happens, it also affects the USB2 ports. Either port type doesn't recognise my disc is plugged in.

'Freezing' happens when the external disc is attached and file copying is taking place. One of several things can then happen. Firstly, and more often than not, the file copy dialog box will appear stuck - no progress occurs. It will remain 'stuck' copying the same file and won't respond when the action is cancelled. The only solution then is to reboot the system as Task Manager won't end the process. When rebooting, the system will then hang on the 'Shutting Down' or 'Logging Off' screen and will only respond to the off switch. On reboot the system will go no further than the Intel flash screen and will hang showing 'EB' in the lower right - it won't proceed to show the boot options nor will it respond to Alt+Ctrl+Del. So, a second switch off is required to get the system to boot properly.

Secondly, at other times, copying will stop and Win7 will show a dialog box with the message, 'Items not found. Could not find this items. This is no longer located in [source drive/directory]. Verify the item's location and try again.' More disturbingly, when this happens all the directories on the USB disc appear to be empty. This is resolved once the system is rebooted.

If I delete the USB3 drivers from Device Manager and just use USB2 the system *seems* to work o.k. But what puzzles me most about this is that I installed an Asus U3S6 adapter in my old system (Intel DX38BT) to give USB3 support and never had a moments trouble from it. Brilliant speed with my disc and very solid. The DH67CF and U3S6 both use a Renesas chip to provide USB3 support, so I can't understand why there is a problem. I have tried earlier versions of the Renasas driver, including the one for my U3S6, but the problems still occur. The original driver was the Intel v.2.1.28.

Any ideas anyone? I don't want to have to leave the USB3 off - it defeats the object of buying this board or indeed a USB3 disc. I am a bit disappointed really. I have only ever used Intel boards and have never had a problem before, which is why I chose this one. Your advice will be much appreciated.

Thank you.

====== Board ======
Manufacturer                       Intel Corporation
Product Name                       DH67CF
Version                            AAG10215-206
Serial Number                      BTCF14200217
BIOS Version                       BLH6710H.86A.0146.2011.1227.1631
BIOS ROM Size                      1024 KB
BIOS Release Date                  12/27/2011

====== Processor ======
Manufacturer                       Intel
Processor Name                     Intel(R) Core(TM) i3-2120 CPU @ 3.30GHz
Processor Speed                    3.3 GHz
Stepping                           7
Form Factor                        Socket LGA1155
Hyper-Threading Technology Status  Enabled
                                  
====== Memory ======
Error Correction                   None
Maximum System Memory              16 GB
Memory Slots                       2
                                  
  ---- DIMM1 ----
  Socket Designation               DIMM1
  Current Memory Type              DDR3
  Installed Size                   4096 MB
  Memory Speed                     1333 MHz
                                  
  ---- DIMM2 ----
  Socket Designation               DIMM2
  Current Memory Type              DDR3
  Installed Size                   4096 MB
  Memory Speed                     1333 MHz
                                  
====== Onboard Devices ======
#Device Type                      Video
  Device Description               Intel(R) HD Graphics Device
  Device Status                    Enabled
#Device Type                      Ethernet
  Device Description               Intel(R) 82579V Gigabit Network Device
  Device Status                    Enabled
#Device Type                      Sound
  Device Description               Realtek High Definition Audio Device
  Device Status                    Enabled
                                  
====== Hard Drive ======
#Model                            OCZ-AGILITY3
  Max. Transfer Mode               UDMA 6 (ATA/133)
  Active Transfer Mode             UDMA 5 (ATA/100)
  S.M.A.R.T. Status                Enabled
  Size                             55 GB