So the problem is not really LW. It could very well be an issue with the new WMP version (unless it's a graphics card issue.) If u can run LW alone without problems, then it's a prob with the software by the sounds of it. Freezing on a mac generally suggests incompatibility or a software clash. There are utilities out there that can check for software clashes. U might be more in the know than me for Windows. One I'm aware of is called Conflict Catcher.
I was just thinking, if it's a dual processor, there might be an issue with how some apps cope. Keeping in mind that video is processor hungry (& graphics card needy.) The earlier mac twin processors had dome issues with some apps in a similar way.