May not be helpful, but I know all too well about the 200m chips. Audio is strangely, also built into those chips, mine fried one day on a minor software change (using another distro).
Just a small chance, but I have an older machine that will steadily have boot/shutdown issues if plymouth is enabled, runs just fine otherwise, but will lock up partway through the process frequently when using plymouth.
I just changed the menu.lst entry from "splash=silent" to "splash=verbose", and my problem went away. You might try it, if nothing else to just eliminate that as being the source of the problem.