I also posted the solution on my blog. Good luck!
I was having the same problem too for the last several months. HERE’S THE SIMPLE SOLUTION!
Completely erase the wp-admin folder and the wp-includes folder.
Then upload a fresh wp-admin folder and a fresh wp-includes folder.
This should work. I’m confident of it.
What I was doing earlier I would simply overwrite the existing folders but the problem would still continue. so this time i decided to completely erase the folders and then upload fresh new ones in their place and it worked! It worked for me and I’m confident it will work for you too!
