This is not a sign that the sim crashed, just an issue with OpenSim grids sending a disconnect event before the viewer considers it is done disconnecting fully. This happens in all OpenSim grids with all viewers I tested since a few months, but is totally harmless.
I cannot reproduce this issue here (got the same avatar name on many grids, and never encountered such a problem when switching from a grid to another with the same avatar name).
My guess is that you tried to log into SL with the name of an Inworldz sim in the location combo box. When this happens, simply select "My Home" in the location combo and try again.