Help! Leopard loses settings every reboot

My MacBook resets itself every time it is shut down or restarted. The dock moves to the default position and the items I have put in it vanish. The desktop photo vanishes although the clutter remains. Opening iTunes after restarting, I must agree again to terms every time. My Safari history and top sites are completely gone after restarting, and mail account has to be started from scratch each time.

The former owner of the MacBook did not have these problems. It is the Intel Core 2 Duo, 2 GHz (MacBook2,1) running Snow Leopard 10.6.8. I moved into it from a 12" Powerbook running 10.4.11 and a 15" Titanium also running 10.4.11 using Migration Assistant, but have now removed Classic and its applications, installed Rosetta, and have thrown away applications that are not compatible with Snow Leopard using CleanApp.

If it is any clue as to why I am having problems, the calendar was a mess with entries multiplying like mad until I disabled something that had to do with synchronising it with other devises.

Can anyone please help?

I suggest reinstalling Snow Leopard, but this time do a clean install. I don't know why you're having all those problems, perhaps it was a bad migration of data. A clean install will help to isolate any problems that may occur. Back up whatever you can before doing so.

Thank you for your reply, chscag. Bad migration of data, indeed!

When the shop replaced the hard drive in my newly-acquired, second-hand PowerBook, I put in my user name and password (the same I used for my older machine) and used the PowerBook for a year without a problem. It was when I tried to migrate to the MacBook that I discovered that the PowerBook had stored my newer files under johndoe, and that I did not have privileges--or the password! Johndoe-- apparent administrator--never had a file under 'Users," so I thought I was the only user. (I had had computers for only about a year, and never questioned why my user file didn't have that little house, although it had it on my older machine.)

After learning about the difference between users and administrators, I thought I could get around the problem on the PowerBook by making myself an administrator. So I did. That caused johndoe to appear under Users with the little house, and lock me out of my files. I tried to get around the problem by signing in as johndoe (I had to hack his password to do this, as the passwords that the shop gave me did not work) I made johndoe give me privileges, and drop files into Sharing. Then I would sign in with the only name and password I had ever used up to this point, take the files out of Sharing, and put them in my User file. This worked for some of the files, but johndoe seems to be a permanent headache in the Powerbook. I am now locked out of some of my files on it.

The files in the MacBook, however, migrated before I made a mess on the Powerbook by making myself an administrator. I was locked out of some files after the migration, but, having discovered johndoe's password, gave the MacBook administrator privileges to everything. However, I think I still have trouble with johndoe. He hitched a ride with the migration, and has a user file in the MacBook, but does not appear at all in the Accounts in System Preferences! (I just now discovered this.). I did not throw away his files because he has all the work I have done in Keynote and probably other important stuff. There is some trash that will not empty, even though all administrators have privileges.

As I prepare for the (dreaded) clean install:

I have purchased a 2TB external drive in hopes of sorting out this mess, but it has no firewire connection. The MacBook has 215 GB used. Will that be a problem?

Would it be best to make a clone of the MacBook, rather than trying to figure out where files are for things like iTunes and iPhoto? (The MacBook has three users now--one for each of the old machines plus the MacBook administrator file, which was gradually acquiring files from the other users, in hopes of eventually eliminating them.)

Should I use Migration Assistant at any point in the new installation?

Do you think I should run ChangeShortName on the PowerBook as a way to get glitch-free copies of my older files so that I don't just reimport problems?