After applying Microsoft 2007 security updates, "Object library invalid" error may occur in SDL Trados 2011. For me, the following steps solved this issue.
1. In Windows, start a "Command Prompt" as an Administrator.
2. A Command Prompt will open.
3. Type the following in the Command Prompt:
regsvr32 /u mscomctl.ocx
and then press Enter. (A popup window will show up and then disappear.)
4. Type the following in the Command Prompt:
and then press Enter. (Once again, a popup window will show up saying that the file has been registered and then disappear.)
5. Exit the Command Prompt by typing "exit."
6. Now, please remove the MultiTerm template, which will be found in the following path:
If you want to use MultiTerm in MS Word, you might be able to move all Trados templates to a separate folder.