Xbox 360 why did i got E68?

OK so like a month ago,i turned on my Xbox 360 and it gave me one red light and on the screen it said E68 so i looked up online and it said it was a voltage error that could be caused by the hard drive,so i removed the hard drive and it turned on fine,i put it in the hard drive and it worked fine,and today i turned off my Xbox 360 but i forgot to do something so i turned it back on again and it gave me E68,turned it off and turned it on after blowing in the hard drive slot and it turned on fine,why did i got this 2 times?,is there something wrong with my hard drive?