Are you sure the "Press U thing" is working?

Option 1

• Try uninstalling Flasher and all drivers that came with it and install everything again.

Option 2

• If uninstall don't work you should check your registry at the location below.
  
  HKEY_LOCAL_MACHINE
  \SYSTEM\CurrentControlSet\Enum\USB\VID_0421&PID_0105
  
  
• If you find it, try deleting the key and all things under it as well. You might need to change the "Permissions.." on the key so "Everyone" have "Full Control" to "Allow" before you delete.
  
  
• Now go back and start from the beginning of my first instruction with a fresh install of Flasher etc.

Option 3

• If the above key is not found you haven't successfully installed the orginal driver or the libusb-win32 driver.
  
  
• Search on "nokia" at the registry location below,
  
  HKEY_LOCAL_MACHINE
  \SYSTEM\CurrentControlSet\Enum\USB
  
  
• Delete all Keys and other thing you feel safe doing related with "nokia".
  
  Worst case, you have to reinstall some drivers for other nokia devices you might have.
  Deleting in the registry is my last resort option for anyone and only recommended if you know what you are doing.

Hope this helps.

//Code