fifthbeatle

I've purchased a (refurb) Gateway 840GM running XP Home SP2 with Media Center 2005. I've tried to attach a DSL router, and the speakers which were included with the system. Both times, when I started the computer after attaching 1 of the above, I get "MBR Error" (no number). Fortunately, Norton GoBack (from SystemWorks 2006) has allowed me to go back to a point in time where I could successfully boot the computer into Windows, and use it normally. I do not have restore CDs, and only have an upgrade copy of XP. Before attempting (the first) restore via GoBack, I could get the system to boot up with the upgrade XP CD (after numerous attempts). Any ideas how to permanently fix this problem?