This is the entire command line directive:
COM(6, 115200)
DEVICE(LPC2368, 4.000000, 0)
HARDWARE(BOOTEXEC, 50, 100)
ERASE(DEVICE, PROTECTISP)
HEXFILE(C:\Program Files (x86)\My Company\My Software\myfile.hex, NOCHECKSUMS, NOFILL, PROTECTISP)
Just to clarify: this is the exact same string I get if I export Command Line Directive from the Flash Magic GUI software.
Just to clarify more: if I use any other path without parentheses (even with spaces, but no parentheses), the command executes fine.