Flash bios on ACER 4520 Laptop

No its a hardware problem, it is getting hot because the power supply fan is not running as it should to keep it cool. You will have to take that one in to get repaired. But don't let them tell you anything else, it is only the power supply so it should not be very expensive, you may even be able to find out on the Internet how to do it yourself if you're comfortable going inside your laptop.
Hope this helps.
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To keep a laptop from shutting off due to heat related issues, get some canned air and at least weekly, blow the intake fans underneath and the exhaust ports along the sides. Also, an auxiliary fan base under the laptop will help a lot. You can download an HDD Thermometer online for free. It will monitor the temperature of your CPU and you will see when trouble is coming. Mine runs from 25-34 celcius. Once it hits 35, it starts to shut off. I just make sure to blow everything out when it starts to maintain 32 degrees all the time. The canned air is cheap and the fans are about $15 & up.