Imac "erase free space" noise won't stop.

[Max37]

I did an "erase free space" last night, it finished this morning. But that noise that sounds that it makes when erasing won't stop. Restarted the computer twice but no luck. Any ideas? Thanks.

 

[basher]

My novice guess would be that the hard drive is trying to tell you that it's about to fail.

If it were mine, I'd be backing up the data and then making an appointment at my local Apple store to have it looked at.