Here is a direct link to my post in the aforementioned thread
word 2007 send to buttton greyed out
I think that your problem is stemming from not having the correct privileges when making the changes to your registry. Because the keys we are modifying are in the HKEY_LOCAL_MACHINE (HKLM) branch, we need to use an account that has administrative privileges.
The easiest way would be to use the batch code I provided and follow these instructions (take notice of the bits highlighted):

Originally Posted by
Dwarf An alternative method is to copy the above code into 'Notepad' and save it with a '.bat' extension. Give it a meaningful name, such as 'Office 2007 Email Patch.bat'. Again, if you click on this file it will merge the data into the registry, providing that you do so in an account with administrative privileges. Alternatively, right click on the batch file and select 'Run as administrator'. After providing administrative credentials, the file will execute and the data will be merged into the registry.