Try to completely uninstall your Office program first:
How do I uninstall Office 2003, Office 2007 or Office 2010 suites if I cannot uninstall it from Control Panel?
Then download Office 2010 trial from the link below, and save it to your local computer:
Boot the computer in clean boot mode and try to install the program by clicking the downloaded files.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
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