Lync 2013 Autodiscovery Key Deleted when Lync is launched

Hi.

We are having an issue with some of our users overseas. They are using Lync 2013 on a computer that's essentially identical to the computers used across the organization. We are having trouble with EWS, so we are attempting to pre-populate the autodiscovery key under HKCU\Software\Microsoft\Office\15.0\lync\~SIP~\. The key is being populated successfully, but when Lync 2013 is launched, the key is automatically removed. Why is this happening, and more importantly, how can we force Lync to always use the autodiscovery key that we're creating so that EWS and other services function normally?

Thanks,

Doug

Douglas Cote