MBR Failure Invalid partition Table

I have a Demension E521 withVista Home Premiumn. I used 3rd partty bootable CD to view MBR.

Entry 1 has al zero's in pairs. which probly means Invalid Partition table.

The Bios see my hard drive but will not let me make it a bootable drive.

I can access the Hard drive if I boot thru a CD.

How can I repair the MBR.

I have Tried bootrec.exe /fixMbr  and /fix boot, and /rebuildBcd

What should I do now.

Mike31z