prob might be 1.u have a non bootable floppy in ur floppy drive. 2.the HDD u have seleted in ur BIOS as a bootable drive does'nt contains any active partition so no MBR has been found during BOOT. do u have 2 diff. hard disk if yes then try changing sequence HDD0 to HDD1 as later might have an active partition. else tampering of MBR cozes bootstrap loss, so try to resolve by reparing MBR by ur oS boot disk. do u have repartition ur HDD coz because repartioning active partition sometimes results loss oF MBR.