I have the same problem, and I have double (if not triple!) checked and the Win51ic file does not exist on my DVD. (I have Windows Explorer set to see all hidden and system files so it doesn't miss anything) In fact to start with the new Asus recovery DVD had an I386 folder and also an i386XP folder. To get nLite to recognise it as a valid source I had to rename the I386 folder (as I386old) and rename the i386XP folder as simply i386. Then when I start nLite and point it at the copy of ALL the files that I have taken from my DVD to my Hard Drive, nLite pops up a warning saying that the "CD ident file not detected! Make sure you copied it from the original CD (and all root files)" and then it goes on "You can copy it now without restarting nLite" and "Copy win51ic to C:\Asus_XP_Source\" with an OK button. When I click OK - nLite appears to carry on and it does identify my copy of Windows XP Home, although without any service packs, and appears to be working - although I haven't yet had a chance to actually try the ISO it has produced to see if it works. My DVD source file is a very new Windows XP (supposedly withwith SP3 integrated) from my new Asus EEE 901. I guess Microsoft have changed something in the latest versions or Asus have done something with their copy. Certainly not all source CD or DVDs have the win51* file that nLite expects so it's not just a simple matter of missing something during the copy process.