I recently had to look over my own personal ADT settings to see why I haven't had any problems at all.

On the screen capture below right, I believe that I have the answer to why I haven't had any ADT Xref loading problems.  A while back when we were first beginning to work with ADT 1.0 and then AutoCAD 2000, we at ARCHIdigm decided to change our Demand load Xrefs setting to Disabled under the Open and Save tab of the Options dialogue box.

The reason we changed this setting did not have anything to do with the current problem some users are experiencing though, it had to do with the irritation of not getting AutoCAD to reload a current Xref file in the target file while being edited in the source file on the same system.  In other words, when you work on both the Xref source file and targe file at the same time and want to reload it so see how the changes look. 

Here's the deal:
If you set Demand load Xref's: to Disabled, it takes longer to load files with Xref's because everything is loaded, needed or not. Others can edit the Xref source.

If you set Demand load Xref's: to Enabled with copy, you get the speed/performance feature of demand loading what is needed.  Others can edit the Xref source.  This is the best option, particularly in a Networked office, but if it doesn't work use Disabled.

If you set Demand load Xref's: to Enabled you get the speed/performance feature of demand loading what is needed.  Others cannot edit the Xref source.

You can also try using "objrelupdate", an undocumented command for ADT that will request what objects you want a full reload of ( you can type "All" ).  This apparently has worked for many people having issues with Xref loading.