If you have not already done so, we would recommend you try moving your consoles to a different location in your home as your unit may need greater ventilation. Also, you may want to inspect your game disks to make sure they are free of scratches. Other things to try can be found by reviewing the steps in the following support article. If you still find that you need help with freezing issues, please go here to get Xbox Support's telephone contact details.
http://support.microsoft.com/kb/907586/en-us
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