I have a custom web part that utilizes a dropdown combobox with items populated from AD. While it used to work, now I am unable to see anything populated in the dropdown unless I view the web part from the server (yet using the same SP accounts).
Tweaking the settings of IIS Manager's Authentication actually allowed non-admin accounts to see the dropdown items, but still only when logged into that server. The same non-admin accounts still could not get the dropdown items to show outside the server.
This tells us that it may be a server level problem and perhaps IIS is preventing users from querying AD.
So far I have tried checking the following things on the server: system security and permission settings, windows authentication methods, re-deploying the web part, and restarting IIS.
Our VM server is: Windows 2008 Server R2 running IIS 6.0, SharePoint 2010 Enterprise
Also interesting to note that this dropdown works fine on our old server (same web part and same code). The server specs for that are the same as above.