There was a patch to lessen the chances of it happening, but it does still happen for some. If it is frequent for you then there may be something particular with some add-on or some way your interacting with your system that may be making it more likely to occur for you. I forget the exact details but I think it had something to do with the skin reloading while the screensaver was active which for some reason was sometimes making the screensaver wake up command not work.