When the CreateResolutionQuery2 function is called multiple times in a Lync Server 2010 environment, the EnableContactMergeUsingProxyAddress property settings create a code loop. The code loop then causes an IP telephone to restart unexpectedly.
This issue occurs because the EnableContactMergeUsingProxyAddress property settings are changed unexpectedly after you apply the update that is described in Microsoft Knowledge Base (KB) article 2498410.
To resolve this issue, install the following cumulative update:
2630294 Description of the update package for Lync 2010: October 2011
To work around this issue, remove the EnableContactMergeUsingProxyAddress property, or use the Lync Server Management Shell to set the property to true.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2498410 A user name is still in Lync 2010 after you remove the user account in AD