I've had that same problem but with poser Pro. closing everything down and rebooting my computer fixes it for a new session. But it does it again if I use P7 first. Some programs have that effect on it. I have WinXP on an EMachine with 1.5 GHZ and 1GB RAM.

Let me introduce you to my multiple personalities. :)
     BluEcho...Faery_Light...Faery_Souls.