Have you made a lot of downvotes? From the About page:
You can only down vote up to four times your current karma (thus if you never comment, you cannot downvote).
I'm on a different computer and the message now says "You need 1 more point", so maybe that's what it said before and I misread, and Pavitra was misremembering it as being one-fourth instead of four times. (Edit: by which I mean thanks and sorry for the mispost.)
Downvote buttons seem to have just stopped working for me, saying I need at least 1 karma. I'm posting in case it leads someone to fix the problem.