Thanks heaps for all your replies. oioldman: As I said I get the error in the filecopy straight after the format, the first one, with the blue background, not the GUI bit. Yes I have looked thru msfn, and it all looks ok. Plus, what is there in winnt.sif that could cause this? zeko: I was getting the same problem when I mounted the image in VirtualPC but that was with Nlite, I'll try again now I'm using PowerPacker. muiz: Ok, cool, do you mean bad RAM in the system that made the disc, or in the one thats actually running the setup? I'll try some new RAM, thanks. Lazy8: Ok, but I'm trying to make a multiboot DVD, using PowerPacker to create the ISO, but I seemed to have the same problem when I used NLite, only with Nlite nero wouldn't burn the 1.2Gb image to DVD as it was a CD image... apparently. Can I use CDIMAGEGUI to create the iso from a powerpacker output folder? Geist420: I've now burnt 2 DVDs and 4 CDs and all with the same problem... different files though. Plus the problem seems to be with the ISO, as it did the same thing in VirtualPC. But as I said that was using nLite, I'll try VirtualPC again now I'm using PowerPacker. Once again thanks for all the replies.