Resetting my computer back to factory settings

Hi, My computer is an Advent 7011. I’m resetting my computer back to factory settings. I have 3 cd’s for doing this. When I put the second cd in, it downloads to about 75% and then I get an error. “Cannot open xyzcomp.err”, press ok and i get “Cannot read from file 437 Application error”. Is there anyone that can help me reset my computer back to factory settings. Thanks Ben..