As mentioned by Gertrude, what is the reason for your reinstall?
I have been trying to reinstall too (see another post earlier) and it has since been a problem to fully complete the installation. I dont think its a full installation as original files remain,
If you need to backup files, i went into Safe mode...and type msconfig in the run section. Then from there, I got an option for selective startup or diagnostic startup. Cant remember which one i chose, however it did restart with many drivers enabled. (allowed me to copy all important files to cd).
Good luck