It doesn't corrupts the data but MAY Degrade the performance & life of HD.
See HD is a Mechanical system, so the more it overheats, (like if you run it A 58-60 degree celcius for longer period of time, the HD performance is reduced.
Use the HDD Themometer to monitor ur HD Temperature. its really good as it takes the least system resources.(about 800KB)
You'll find the HDD Thermometer here
http://www.rsdsoft.com/downloads.php4