I'm having exactly the same problem - if it's relevant, I'm using Vista Business Edition, with UAC switched off. I am an administrator on the workstations too. Sophos antivirus is installed, but on-access scanning is disabled. I can slipstream service packs without difficulties, but any hotfix crashes nLite with no useful error messages. Cheers, Steve The situation is the same here running Vista Ultimate, I'm administrator and have UAC switched off, but I'm using McaFee Anti-Virus, allready tried to disable on-access scanning with no result.