I had this problem on a brand spanking new custom built windows7 home premium machine with 8 gigs DDR3, 3.2 Ghz intel I5 (bought it 4 days ago, and uploaded all my SD stuff first.) while using the regular fences. My last PC didn't have the umph to run deskscapes smoothly so it was the first thing I wanted to do with this new machine.
Simply reapplying the dream, or picking a new one got things back in working order for me.
It's only happened a few times after changing dreams many many times in the last four days. It doesn't seem to be connected to any one dream as it doesn't always occur with the same dream each time. it has happened with low to high CPU usage dreams, and only happens when changing dreams.
I think it has something to do with the total CPU load at the time of changing the dream that causes fences to lock up. For the few times this occurred, I was multitasking to the max. it's never happened while running dreams all by itself or with just a few lighter programs running. Only when I have a lot going on. Why this would affect fences and not deskscapes 3 is a mystery. It seems as though the issue is with fences and gadgets running on "top" of the deskscape environment more so than than any of the single apps themselves, and keeping all this straight is just too much at that heavy load moment. Maybe that's why fences takes the hit as it's the lighter program and is deemed low priority????