vista error expanding files

When istall gets to expanding files (6%) i get errror message "an error occured while preparing windows setup to boot into the next stage of setup" this happened while trying to install up grade AND when I tried to boot from teh DVD to do a "CLEAN" install
GET READY system scan showed my system was ready for the upgrade. ..only update needed was for the internal video card (which I do not use..an intel chipset video card) I use a nivida 256MB PCI card on a dell deminsion 2400 with a gb of
ram and plenty of HD space)