I don't know you version of add-in, you spoke about 11.0.1 CHF5 (126.96.36.19906) ?
You can find the binary versions on this page : https://www.veritas.com/support/en_US/article.TECH70211
Have you try to use the last version the 188.8.131.525 ? (you can download it on this page https://www.veritas.com/support/en_US/article.100034312)
By experience you can havem ore than one version of difference by EV Server and Outlook Addin.
Other solution, make an upgrade of you EV server in version 11 SP1 CHF5 and use Outlook Addin in version 12. I think that if you are in version 10 of EV, your EV servers are already on Windows 2008 and that's easy to make the upgrade.
this sound like you have problems with office-word component.
Find winword.exe and right click to try a troubleshoot.
I would contact your microsoft partner to have him look at it, if above step didn't work