Weird ps3 rebuild hard drive message


#1

o i was playing sf4, then i got kicked off psn. then i hit the home button and it froze on that screen, sop i turned my ps3,off, when i turned it back on i got a message stating " ps3 was going to rebuild my hard drive" wtf does that mean. I hit okay because i had no other option, and so far it seems like nothing has changed?