I had tried nearly everything to get Endnote X4 and Word to work together. We are in a corporate environment and although you can use Solution 13 from the FAQ section it is good to note that this solution is likely for a standalone computer.
I had phoned Thomson Reuters support and they were only able to refer me back to solution 13 and only stated it was a permission problem but could not guide me past the posted solution.
Here is the altered version where I was able to get all networked computers to stop the Invalid Class String with X4 and Office 2007
YOU MUST HAVE PERMISSIONS TO CHANGE USER SETTINGS ON YOUR DOMAIN
1. Close all programs
2. Do a windows search on the local computer for regedit (normally in C:\WINDOWS)
3. Right Click on the Regedit.exe and RUN AS… the local administrator (if you are using the client’s profile)
4. Select Ctrl + F and search for EndNote14.AddinServer
5. You should find the two keys below if the program is closed;
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{575B6FEB-477B-4595-A478-9B141A98D869}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\EndNote14.AddinServer
***OR***
HKEY_CLASSES_ROOT\EndNote14.AddInServer
6. On the lefthand side of the regedit, right click on the key and select permissions.
7. Click on Add
8. From the Select, Users, Computers or Groups, you MUST SELECT YOUR DOMAIN from location - not the local computer.
9. Enter EVERYONE and click on OK
10. Enter your network credentials
11. Highlight the “Everyone” group and in the permissions, under the allow column, click on “Full Control”
12. Click on OK, Repeat this on the second key.
If you are missing either key, open notepad copy and paste the info below and save the document as EndNoteinvalidstringclass.reg.
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\EndNote14.AddinServer]
@=“EndNote14.AddinServer”
[HKEY_CLASSES_ROOT\EndNote14.AddinServer\CLSID]
@="{575B6FEB-477B-4595-A478-9B141A98D869}"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{575B6FEB-477B-4595-A478-9B141A98D869}]
@=“EndNote14.AddinServer”
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{575B6FEB-477B-4595-A478-9B141A98D869}\InprocHandler32]
@=“ole32.dll”
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{575B6FEB-477B-4595-A478-9B141A98D869}\LocalServer32]
@=“C:\PROGRA~1\ENDNOT~2\EndNote.exe”
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{575B6FEB-477B-4595-A478-9B141A98D869}\ProgID]
@=“EndNote14.AddinServer”
This worked on the first six Windows XP computers that have had multiple different versions of EndNote Installed.