I believe that Sony is opening every audio interface on the machine whenever the program starts. For some reason, it doesn't get along with the JRiver ASIO interface. I don't understand why they do this, but they must have a reason.
I thought that they recommended installing their software after ours, but order would not normally matter.
I'm a programmer on the Sony Vegas team. I agree with Jim that there's no war between Sony and JRiver. Generally, we've not found a lot of overlap between Sony and JRiver users.
My best analysis of the situation is as follows: We discovered a crash related to the JRiver ASIO plugin back in early 2014 and reached out to the JRiver team. It seems that Vegas (Vegas and Movie Studio have a lot of shared code, so they behave similarly in this regard) is unusual in that we unload unused ASIO plugins that we don't need to save memory. Most ASIO hosts don't do that, so it's not a commonly tested feature in ASIO plugins. Well, we think (see below for deeper details and caveats) that JRiver crashes when it's unloaded. After an email conversation with the JRiver team, we were unable to find a solution so Vegas Pro 13 took the simple step of skipping the JRiver plugin -- that is, we never load it so we never hit the unload crash. That completely solved the problem for Vegas.
We did not add that same workaround to Movie Studio 13 (it was released before we learned of this problem) so I believe that it's still encountering the unload crash.
To be clear, I'm not pointing fingers or trying to place blame. I'd love to find a good solution that works for both products without needing to have a special-case for JRiver. My team believes that the crash is in the JRiver ASIO plugin, but we admit that we're accessing the plugin in an uncommon way and we can't really prove that my analysis is correct or incorrect. The only evidence that we have is that after unloading the JRiver plugin, Microsoft code is crashing trying to access something that's missing, so circumstantially we think it's something left behind by the JRiver plugin but there's no way to know for sure.
I hope that clears things up and perhaps helps some JRiver users find workarounds.
Chris