Doom 3 : RoE -- I need tech help!

all i can think of is that the there's some minute difference in the installer between doom 3 and the expansion and maybe running a newer operating system mixed with that could cause the code fairy to come and pineapple something up. what's your operating system? i know i've got doom 3 and resurrection of evil in the garage somewhere, i'll see if i can get it to work on my notebook