Thanks for the info Shawn. I think I ran into something similar a while back (if I recall, using the UltraTree, if the nodes were off the screen and the scrollbar was visible, doing something with them programmatically caused a null ref exception, but that's assuming my memory is correct). 

As far as my issue goes, I haven't been able to line up a time to upgrade and roll it out to our customer, so I have no new update.

If you could keep me in the loop that would be great! I was hoping the stack trace would be able to tie to a specific bug fix.

I'm going to have to see what we can do to upgrade the controls, rebuild and get the application to the customer in a reproducible scenario, but sometimes that's not always easy. But I will for sure try and report results if we're able to. In the meantime, if any new information comes up, please let  me know!