U/s 143 intimation with tds showing 0

Hi,

I'm a salaried employee. My form 16 shows TDS. I had filed the same in my income tax return for A.Y 2012-13. Today, I received a "Intimation U/S 143" in e-mail. According to it, it shows TDS as 0 under column "As computed under Section 143(1)". What does this mean?

Finally, it seems to be demanding that I pay all that tax now. This seems like an error somewhere. How do I go about resolving this?

Thanks,

Vinay