i think your software maybe the problem have you tried record now max? it's more reliable i've never got a coaster unless it was my fault (wrong setting ect)
www.stompinc.com
it's a 30day trial but well worth paying for
i'm sure most people would agree about this RNM
also make sure you choose ISO on RMN not global image
i don't know about anyone else but that's what i have to choose one i've made my iso with craxtion
or choose the data burn method for RNM there is a very good sticky on this forum for it