If you are running Office 2007, and you are unable to open Office documents from SharePoint in IE, try the following to solve the problem.

1. In Windows Explorer, navigate to C:\Program Files\Microsoft Office\Office12
2. Delete owssup.dll (I was able to get it to work after doing this)
3. Run the Office diagnostics by selecting Start > All Programs > Microsoft Office Diagnostics. This tool will find the missing component and install the “correct” version.