I forgot to mention that this workaround is not perfect: when using Compiz, the windows rendering content using hardware acceleration leave a trail (old content not redrawn) when you move the window and/or are not rendered are rendered on only one workspace (sometimes not the one you would like) when the window is on a side/corner and has pixels in another workspace. Some apps such as Google Earth behave therefore strangely when the window is placed on a corner, but at least no HW freeze as I was getting doing that on a freshly installed Karmic.
I forgot to mention that this workaround is not perfect: when using Compiz, the windows rendering content using hardware acceleration leave a trail (old content not redrawn) when you move the window and/or are not rendered are rendered on only one workspace (sometimes not the one you would like) when the window is on a side/corner and has pixels in another workspace. Some apps such as Google Earth behave therefore strangely when the window is placed on a corner, but at least no HW freeze as I was getting doing that on a freshly installed Karmic.