Romangirl,

As i cannot see your screen, everything is just a guess.  In my horrible experience using pc's its almost always the video driver.  You can try searching for a newer driver, or research google on that video card's stability issues.

I wasn't suggesting you were out of memory, but maybe hard drive space?  If you have windows 8, it must be a fairly new computer, and you "should" have plenty of space and enough memory to run poser.  If you crash ONLY during the render, you may want to check your render settings, and lower them.  There are way smarter people in here about what the settings mean and do, but lower the size of your bucket and see if that helps.  Make sure you are not running anything in the background when using poser for rendering. (it frees up memory).

You "might" get an answer to your crashes in Settings, Admin, Event Viewer.  Sometimes, the messages in there actually help.  I'm guessing subfolder Applications, look for poser crashes.

I hope it helps.  Google is indespensible for solving these types of problems.  Usually someone has already had them.