When trying to boot with a disc, it's say that the disc isn't compatible with your machine. ( I thing strongly. )
After you start up the machine normally, can you insert the disc?
You can manually delete things. You might miss a few things but you should get most.
start by deleting your id:
Create new Account
blue apple > system preferences
clicks on accounts icon
click on lock icon if locked.
enter logon password
click on + icon ( left side of screen just above the lock icon )
after creating new account, you need to logout of your current account.
blue apple > log out ... current count name ...
log on to new account. see if problem goes away.
if it has gone away rename finder preference ( Not sure of name ) ... reboot.