This is a yes/no kind of answer. As far as hardware goes there is very little chance of you damaging anything. When you unplug it you are basically stopping anything that could cause a problem. However, if you are in the middle of saving or installing something then it might loose data or overlap the data when it attempts to do the same again, which may or may not result in system errors or kernel panics. To be on the safe side I wouldn't unplug it too often as it could lead to errors. I know that our school PC's get glitchy when they are unplugged because I have to fix them most of the time.
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