Conflicting outlook add-ins

If I install the Enterprise Vault add-in for outlook 2010 first, I can double click on an email and it loads up fine. After I install a add-in from a different company, all the email come up saying there was an error loading this item - some functionality may not be available. If I click on that I get an error message that says "The handle is invalid. 80070006"

I can view the email in Archive Explorer fine however.

Enterprise Vault add-in 10.0.2.1112, Outlook 2010.

Any idea's on where to start? I've tried removing/reinstalling both and it's the same thing everytime.

Thanks!