dell inspirion 8500 wont boot

so did a full fdisk/format/reinstall on the thing, reinstalled everything that i wanted, not all the software garbage that comes on the computer, and now it will only boot if i start off the dell diagnostic cd first. it restarts fine after i get it started, but when i try to boot after just turning on the computer it doesnt.

it was running very slow is why i did this, was time to clean it off. what happens with a dell if you fdisk all the partitions? do they have some hidden partitions that make the machine not work after. thx