I have yet to discover the ability to reinstall/repair internet explorer 7 within Windows Vista. In Windows XP within the program directory, there was an uninstall utility. Although I have never used it, I imagine you can wither completely remove or repair an IE7 install in this way. In IE6, you could right click on the ie.cab file in the program folder to reinstall internet explorer and repatch the application after the fact. No such luck with IE7 on Vista...
I recently installed OMEA reader from http://www.jetbrains.com which I like very much as this program enables me to read my RSS feeds and newsgroups within the same program. Since installing this program, I found that I needed to disable the plugins that it added or be faced with a delightful Visual C++ runtime error and have the application crash in my face. The interesting thing here is that this was the outcome even if I selected to run IE with no extensions from the shortcut or from the Run command with the -noext switch.
If however, I run IE as administrator, everything works as if nothing was wrong. I enabled the Internet Explorer verbose logging function to attempt to grab some output that I could use in troubleshooting. No such luck... Maybe we'll see some better troubleshooting tools for Internet explorer pop up as the adoption of Windows Vista increases.
Incdentally, I had posted awhile back that I am unable to access the http://www.owsug.ca website while using IE. It turns out, that by running IE as administrator, this also works making this some sort of security or elevation of privilege issue. If I manage to ferret the problem out, I'll be sure and update this post.