Newer USB flash drives are being made to be Fixed rather than Removable to comply with Windows 8’s Windows to Go functionality. And there are several manufacturers who are complying with this requirement. So, when you buy a new flash drive check to see if it’s Windows 8 compatible and if it is buy something else.
You might also write to Sony and ask if they are going to patch their systems to support the new Microsoft direction.
More info here: http://www.microsoft.com/en-us/windows/enterprise/products-and-technologies/devices/windowstogo.aspx
