Ok, I remade the disk in stages, firstly adding SP3, IE7, and WMP11. Tested on a VM and it worked. Then added all relevent hotfixes, and tested again on VM, worked fine. I'm leaving out the .net framework as I suspect that's what caused the error last time. At least it's working now, I'll just download the .net framework from windows update, it's still less hassle than downloading 40+ updates. Thanks for all the advice anyway, nLite is a brilliant tool