Have you read the "Troubleshooting" section under the latest release thread http://render.otoy.com/forum/viewtopic.php?f=45&t=27251? That may help. Also, if it is crashing whilst rendering a long animation, there is a very high likelyhood that it is a video card overheating issue.
When I try to stop a render in progress, it's very slow to respond. Then the set up window will not allow me to change panels from the animation panel to the settings panel. I have to shut down the plug in.
On large scenes, if you have only 1 graphics card, both Windows and Octane will be using the one card and the Windows (and therefore Poser) GUI will be slowed considerably. It is highly recommended that you use a separate display adapter for Windows - you will be blown away how much better Poser runs if you have Windows using your on-board graphics adapter, leaving Octane to run on your GTX 660.
There are a couple of threads here describing how to get Windows to use your on-board graphics, but in summary, Control Panel -> System -> Device Manager -> Display Adapters, and select the on-boards graphics. If on-board is not an option under "Display Adapters" you will need to change your bios settings so that Windows picks up the on-board graphics as a second adapter.
Using the on-board graphics as your display adapter may assist with your overheating issue too.
Paul