I'm assuming as it was a 60GB the console is around 4 years old, does it just freeze for no reason meaning if you load it to the xmb and do nothing else does the screen freeze there, is there any pixilation, picture distortion, this is very common in ps3s over 2 years old, it will be over heating and need a good clean out and reflowing, restoring files option in the recovery menu is for corrupt hard drive, I don't think this is your problem although doing it will do no harm so go nutz.
If I were you, I would put back the 60GB disk & see if it makes a difference.
Then, I haven't had a lot of media in the PS3. Does yours have ? It might be that the PS3 is busy, parsing through the headers of loads of MP3s and Videos, stored in the hard drive.