i am not sure sorry.
what is the error displayed please?
maybe have a look here 'Data Execution Prevention prevents complete booting or shutting down' (about halfway down page) click here
i also remember reading something lately about disabling the L2 cache in the bios temporarily if there are problems installing sp2 with an athlon 64 but cannot find the info at the moment sorry. I may be way off track here and may be wrong. somebody more knowledgeable will know.