Seems to be independent of flags, but I used -O -Tpdf .
Input file: b1946.gv
[ellson] I don't understand what you mean by "diverges" ? Are you saying that dot produces good output on the test case, but bad output if a single "-' is removed?
I can't reproduce this on Linux, so it may be specific to the Windows version.
It sounds like you are switching graphviz versions a lot? Could you double check that this problem occurs on a recent version of graphviz by checking "dot -V" ? (I'm concerned that you might have multiple copies of dot installed.)
dot hangs with the input graph.