osx wont accept admin password

Help Please!! I have a 5 year old IMac running Leapard. recently the OS started to misbehave so I reinstalled the OS and restored the whole machine from my time machine backup. this worked fine!! However my log in is now only "standard" and when I try to do anything that requires admin privileges, the OS does not recognize my name and password .

This is what I have done to date.

changed password by booting up with OS DVD
changed password from system preferences
checked admin name from ID on the Terminal

I know my name is correct from the terminal'
I also know my password is correct from the hint given on third attempt

Can any one help, machine wont back up or let me install anything, I'm pretty stuffed here

Boot the machine in Single User mode (command s) and create a new user direct from the command line (terminal). See this Link. Create the new user with Admin rights.

Log on to the new user admin account. Move everything from the old user account to the new one. After verifying that everything is working, delete the old user account.

thank you for your response, but wont i need the original user name and log on in order to migrate everything from one account to the other.

what do you think of installing snow leopard on top, do you thin this could fix the failure to recognize the correct name and password

Once you have created the new Administrator account, log in as Administrator, open Accounts (Users and Groups), unlock the pane, select your old account and click the checkbox to Allow user to administer this computer. Close window, log out and log back in as yourself, and you should now have administrator privileges again. Unlock a system pref to make sure.

tried to create new administrator, but machine does not respond to "command s" on start up, so i cannot start machine in single user mode, tried to run the script from the given link in my standard log in , password request comes up but machine will not let me enter one, ie no key strokes are being registered under the password input...any ideas...

fixed!!! using very nice solution...

boot up in single user mode

What you have to do is!!!

Follow exactly.type

mount -uw /
Press enter and then.
rm /var/db/.AppleSetupDone
Press enter again then type
shutdown -h now

Follow those steps exactly and then it will work.

This allows you to create a new administrator account as if the computer is new. use a new log in name and password this is important....when you boot up and log on it will appear that all data is lost, but if you log out you will see your old log in which will let you in with your old password. but your new admin name and password will allow admin access to your old account, this link explains all:

How To Create A New Administrator Account - Hack Mac