Hard drive read error after encryption

[Blessing Mahomva]

I encrypted my 60gig pool of the 160gig hard drive on the HPNAS 3 in 1 docking station, after one full day the pool was still encrypting and indicating that there is a hard drive read error. The message also indicated that it is a hardware error. After disconnecting and reconnecting power as advised by the error message the error was still there. The error later disappeared after deleting the pool and recreating it.
Since then the docking station has been working well. What might have caused this disk error? if it was truly a hardware problem is it likely to appear again?