Each time I have attempted to change a newly joined BO's costume for the first time, I will get DCed at least once. I do not know if this is because of the music I am hearing during the process or what, but it is a very frustrating issue.
This happened once to me as well. I actually didn't file a bug report, as I didn't make the causal connection between the costume change and the DC.
A semi-interesting side-bar. While changing my boff's costume while in sector space, I noticed that my boff in the preview area of the tailor window was affected by the lighting conditions in sector space (someone went to transwarp and the lighting of the boff changed slightly while it happened).