Seedz,
Try this. Do you have a backup of the xboxdash.xbe file that was on your factory hard drive? If so, just ftp it back into your xbox. If not, you must crack open your xbox, remove the large drive you have in there, replace it with your factory one, boot up with the Slayer CD.
Slayer should set up ftp on the xbox with IP number of 192.168.1.200 if you don't have a DHCP server in your home network. If you do, just turn the TV on and see what IP it received.
Now use a FTP client to ftp into your xbox. Just to be sure, copy everything from your xbox to your PC, and save it somewhere for safekeeping. Once that's done, go into the C drive, grab a copy of xboxdash.xbe and put it on your desktop.
Now replace your factory hard disk with the new one you had there before. Boot up with your Slayer CD again, ftp into it again, and replace the xboxdash.xbe you have on your PC's desktop onto it. Take out the Slayer CD from your xbox and reboot it. See what happens then.