Formatted a machine at work because of hal.dll error and reinstalled windows - everything is ok now as it's working but when booting it asks me which windows I want to boot from, the new one which I've just installed or the previous one which still contains the hal.dll error. I can't understand this because the format completed 100% and took a long time as well. How do I get rid of it? What did I do wrong? Is this detrimental to the running of the computer?