Hi @colonethan36
I have a couple of questions:
1. What type of file are you trying to open?
2. Is the file stored locally (on your computer) or externally (on a network share or cloud)?
3. Have you tried deleting your Mudbox preferences so a fresh, default set of preferences could be auto generated by your next launch of Mudbox?
The error you are getting is very strange. I have never seen it before.