Black screen, sometimes reboot

My Vostro 400 has been working fine and have the automatic update turned on so don't really know what has been changed recently.  However it just started rebooting going to black screen, no blue screen, no Windows log messages about it.

Then it started going black screen without  a reboot anc coming back to where it was it app wise.  Sometimes it seems printing will trigger it but not always.

Any ideas?