During the week my macbook hard drive bit the dust. I had a new hard drive installed today and I migrated my old data over to the new drive from backup when I got it home. So far so good - except when I try to log-in to my migrated user, the password simply doesn't work. I've tried lots of alternatives, even though I'm 100% sure I know what the password is. It's simply inconceivable that it can be anything other than what I think it is! I tried resetting the password of the user account in question through another administrator user account, but even the new password doesn't work when I log out and try to log-in to my old user again. I've tried going in through the master password (honestly, I have no recollection of even setting a master password) but nothing that I type in works for that either. I only have a very limited pool of passwords and I've tried them all. It's not a caps lock problem or anything. I was running Lion on the account I'm trying to re-access from my old hard drive, but the new drive is running Snow Leopard. Could it be something to do with this? Failing that, is there any other way to reset the password? I'm absolutely at the end of my tether here and any advice would be much appreciated.