HELP! Can't access my iMac OS X

[osartist]

OK, my husband is the computer whiz but he is out of town on business and my daughter is gonna have complete meltdown if she can't get to her itunes. =)

We recently installed OS X on her system and she enabled the password on startup. Never had a problem until today. It suddenly will not recognize the password. We have tried starting the system off the system disk and resetting the password and even that has failed. Has anybody else had this problem?

Please remember that I am NOT the computer whiz and so need very detailed information if anybody has any suggestions.

 

[jsw]

Just out of curiosity - and I don't mean to imply that you didn't check, but it's possible to forget - is the "caps lock" key on?

Edit: never mind - you said you reset it.

Edit 2: By "password on startup" do you mean when starting the Mac, or when she's trying to log on (i.e., after it's started, when it presents a login screen with, among other things perhaps, her name and a box for the password)?