I have been watching this forum from almost day one.
I also noticed that many of us are having the same issues, and that many cannot get this to work.
here is a tip... how about going back and re reading the whole forum. VERY EARLY ON in this forum there have been a number of people who have posted the same link to fix this issue NO ONE can say why it works.
Ive noticed that in this fast paced soceity we all live in, we want everything fixed yesterday, lets slow down and breathe. here is the link that was given to me to help fix the problem trust me IT WORKS IF you follow the steps in the same order that they are written in.. NO SHORT CUTS...
I also defragged before reinstalling....
I cannot take credit for the hard work of a person called andrewfromparkes rather i can only thank him for taking time out to get the knowledge to fix this issue and also for sharing this information.
MY advice to others would be slow down and breathe.. there is nothing that cannot be fixed if you take the time to read and breathe.
http://support.apple.com/kb/HT1923?viewlocale=en_US