I'm not at home but did a quick look. If you inspect all your model groups in Notepad++ you need to delete any of the models inside the group that have the same name as the group because its a causing a recursive loop. That's really not a legal group and you shouldn't be able to create that situation. You must have done it way back before we put the naming checks in the code. See how these two lines the first model in the group is the same as the group name. And if you really have a single model with that name then that's also a problem. I think what happened is we forced you to rename the model a while back but the code that fixes the model name doesn't go find it in all the groups and rename it there also so you ended up with these invalid group members. Previously the names were just ignored but with the new code it's trying to recursively load the group members so if you use the same name inside the group it gets stuck in and endless loop.
<modelGroup name="Cascade" models="Cascade,Cascade2,Cascade3,Cascade4,Cascade5,Cascade6,Cascade7,Cascade8" selected="1"/>
<modelGroup name="Icicles" models="Icicles" selected="1"/>