Try again from c:\garmincure3\ (you have a very deep directory structure)
Delete the temp folder and the rgn file
Open Garmincure3 as administrator
Drag the gcd file into garmincure3
Press Make Firmware
Get your device into pre-boot mode
Select USB and flash.
(Remember Cure is not bootable, It's just used for access to the internal Storage, Later you have to flash again in original mode)