When I reinstalled XP SP2 retail version and typed differnt username then it wont accept through activation and i tried to reformat and start again and typed my name as first one then it went through ok so think it may depend what you typing your name during installation if it same when you install at the begin like this x.x.xxxxx that if you typing same name with dots during reinstall many time then activation usual accept but without dots or middle name then it wont accept is it quite strange??