Then login into your spare administrative account and have a look. If you don't have a spare one (why not? it's necessary as you see now) boot into safe mode and log in into the secret administrator account. By default it doesn't have a password (unless, of course, you changed that yourself).
All was fine until yesterday..
my system was running bit slow so i decided to remov some programs from msconfig in startup section..
after deselecting few of dem.. wen i clicked apply a error popped up saying dat i dont have privelege n ol dat regarding adminisrative rights..
i only have one account wich i had been using since long and dat account of mine administrator..