Well, I'll give you a long shot suggestion. How tied to Office 2007 are you? Do you have an older version? If so, uninstall Office 2007 and try installing an older version. If everything works well after doing that, you can then try to install 2007 again if you need it.
BTW - I know this is a horse / barn thing, but circumstances like this are perfect examples of why EVERYONE should use a disk imaging utility on a regular basis.