Actually it's not an issue with the drive. Although it's contributing to the problem.
Leaving your Wii in the sun will cause the motherboard inside to swell and bend from the heating up and cooling down process. You have created bad solder joint inside the Wii. When the Wii powers on, it takes minimal power consumption. Thus working fine at the dashboard. When you put in a disc you cause the Wii to draw more voltage / current and therefore process more electricity throughout the machine. the cold / bad solder joints are failing in the process of transferring electricity to components causing the freeze.