Why does the desktop Hard drive icon keep moving? Every time I log in to one specific account on my mac the hard drive icon, usually in the top right, has moved to the top left and is partly off of the screen. Even when I drag it back to the right it has moved on the next start up. Any ideas how to fix this?
It looks like your hidden .DS_Store file in your Desktop is corrupted, which will cause this issue for sure. 

You can restore this by using Terminal. 


Open Terminal.app
Type cd Desktop
Type ls -aF
Now, if you see a list of all your Desktop items, you're in the right place. And make sure you check whether or not the .DS_Store file is there
Now, type rm -i .DS_Store
When you're prompted hit 'y'
Log out and in again


Mac OS X should have rebuild this file and your icons should be ok. Let me know if you have any issues with the steps, I'm glad to help you.