CREDIT:
http://support.microsoft.com/kb/299699
1Click Start, click Run, and then type path\setup.exe /l*v C:\Officelog.txt in the Open box.
In this example, path is the path of the location of your Office source. The command creates the verbose log file, Officelog.txt, on the root of drive C. You can specify any path and file name for this log file.
Click OK.
Start WordPad, and then open the log file that you created.
Review your log file to find the name of the transform that was used to install Office on your computer. The transform file has an .mst extension.
Click Start, point to Search, and then click For Files or Folders.
In the Search for files or folders box, type the name of the transform, and then click Search Now.
In the Search Results pane, right-click the transform file, and then click Rename.
Rename the file that with the .old file name extension.
Click Start, click Run, typeregedit, and then click OK.
On the Edit menu, click Find.
In the Find what box, type the name of the transform, and then click Find Next.
Delete the registry key that is associated with the transform, and then press F3 to repeat the search.
Repeat step 13 to locate and to delete all registry entries that are associated with the transform.
The following registry location may contain entries for the transform:
HKEY_LOCAL_MACHINE\Software\Classes\Installer
Quit Registry Editor.
Reinstall Office by using your OEM Office CD.