"Authentification Token manipulation error"

So I just bought this computer off Craigslist with Ubuntu on it.

I was a complete retard and changed the administrator password and forgot it among people coming in and out of my room.

I followed this http://www.psychocats.net/ubuntu/resetpassword

BUT, every time I tried to put the password in for the second time to confirm it, I got this thing saying "Authentification Token manipulation error" or something to that effect. What is this and how can I easily fix it?

Remember, I am completely new to this and dont understand ANY ubuntu lingo, so please be explicit.

HELP

I might also add

that I have read several other forum threads regarding this issue and apparently every one of them involve someone who has a lot more experience with linux/ubuntu than I, so I don't understand any of the lingo, that's why I am here.

okok, so I fixed it. From ALL

okok, so I fixed it. From ALL the complicated bs I read, the thing that ended up working was going into the 'read/write' part and typing 'read/write' in the box below. Apparently it was "mounted" read only.