I was having the same problem. I opened the folder where i was keeping the vista files (in your case "D:\Vista\") and i found a folder named "[bOOT]" that contained the file "Bootable_NoEmulation.img". I deleted the folder and after that vLite went on to create the ISO no problem. I haven't tried installing from the ISO yet, so I can't say that the process was successful. But the ISO itself was created with no further complications.