It has nothing to do with your browser. You actually break that section of the webpage page for everyone else, too, regardless of what browser they use, so you may want to edit. The problem you're running into is in the lists within lists.
I'd recommend clearing the LIST mark-ups from your post and just using INDENT, and then, once everything is as you like it, select each section varying in indentation and use the LIST button to save yourself a lot of re-typing or copy/paste work in the markup.
Eg.
If you have...
<Section I>
<Section II><IA>
<IB>
<IC><IC1>
<IC2>
<1C3>
Just go ahead and grab each block and hit the LIST button from the Advanced Menu to arrive at...
- <Section I>
- <IA>
- <IB>
- <IC>
- <IC1>
- <IC2>
- <1C3>
- <Section II>
Which would look like...
[ LIST ][*]<Section I>[/LIST ]
[INDENT ][ INDENT ]
[ LIST ][*]<IA>
[*]<IB>
[*]<IC>[/LIST ][INDENT ][INDENT ]
[LIST ]<IC1>
[*]<IC2>
[*]<1C3>[/LIST ]
[ /INDENT ][ /INDENT ][ /INDENT ][ /INDENT ]
[LIST ]<Section II>[/LIST ]