Hi Andrew,
Welcome to this Microsoft Project newsgroup
Are you using a full version of Project or an upgrade? If you're happy with
editing the registry, save a copy first in case it goes wrong, then search
and remove all references to Project. The try and install again. If it's
an upgrade, you'll have to reinstall the earlier full version first. What
version are you installing?
FAQs, companion products and other useful Project information can be seen at
this web address:
http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on
Mike Glen
MS Project MVP
See
http://tinyurl.com/2xbhc for my free Project Tutorials