I'd still have a look in your mySQL error log (you'll have to find it. It's called hostname.err where hostname is the name you gave your computer and is usually either in /usr/local/var or /usr/local/mysql/data) and see if mysqld is complaining about anything when it starts up.
Also, I've got a syntax question. In almost all of your logins, you have something like
-p=my_password. Do you actually use the
= ? If you are, it may be screwing you up. When I provide the password on the command line I usually do something like
mysql -u root -prootpassword
Note that there is no space between the -p flag and the password. The other thing to try is the -p flag without any arguments (mysql -u root -p). MySQL shoudl then prompt you for a password. Enter it and see if that works.
And a final thought. I saw this
thread where the guy was pulling out his hair for a similar error message. It turns out he had a reserved character (&%#@) in his password. As soon as he changed to a password that didn't have one, mysql worked fine.