Beryl 0.2.0 SVN
A few days ago, I upgraded my beryl installation to the latest Subversion version. The result was that I could no longer use it.
Today I found the solution. In the beryl manager choose desktop and turn off the bottom setting, I think it was called preview icons or something. It came after the rain effect.
*edit* in fact, it is under extras, it is called window previews.