I would suggest, if you haven't already done so, to do a clean boot before attempting to install Office 2010 again. Most of the time the methods above resolve the issue. However, some antimalware/registry protection applications can block access
to the registry and prevent legitimate applications like Office from completing setup. By doing a clean boot you can (usually) bypass them from loading and it may allow setup to complete. If you are still unsuccessful, I suggest you call 1-800-Microsoft
for some assisted support since it may be too complicated to resolve in a public forum. Microsoft does not charge for support when attempting to install our products, so the call is free and the support is free. :-)
Bob Cooley Supportability Program Manager Microsoft Corporation
In addition to the above, if you are not sure how to do a clean boot you can look here for instructions:
http://support.microsoft.com/kb/929135
Bob Cooley Supportability Program Manager Microsoft Corporation