After installing new card and board drivers 'My Computer' is not displaying some attached USB devices and therefore I cannot access them.
For example, I have an external USB HDD. It is drawing power from the USB port because the power light is on but it's 'icon' is not displayed in 'My Computer' nor is it displayed in Device Manager. But I have a Topfield PVR which is not displayed in 'My Computer' but is displayed in Dev Man. And for some strange reason USB flash memory sticks are displayed in 'My Computer'