Arduino Due.. Can't compile

Morning, I have win 10 and downloaded and installed SAM core, but on compile of known working sketches I get the following error

Arduino: 1.6.5 (Windows 8.1), Board: "Arduino Due (Programming Port)"

Build options changed, rebuilding all
arm-none-eabi-gcc: error: C:\Users\Main\AppData\Local\Temp\build3037541676499572887.tmp/core/syscalls_sam3.c.o: No such file or directory
arm-none-eabi-gcc: error: C:\Users\Main\AppData\Local\Temp\build3037541676499572887.tmp/core.a: No such file or directory
Error compiling.

Can anyone help me please, I have never tried Due before and am lost on this item.

Thanks very much in advance.