It's not letting me into the BIOS setup at all even if I press the delete key.
Obviously not that then, look at the first bios screen above where you get the error message, what is it listing as your first IDE master ?
It says exactly this:
"Auto-Detecting SATA 1...ATAPI CD-Rom
Auto-Detecting SATA 3...IDE Hard Disk
Auto-Detecting SATA 2...ATAPI CD-Rom
Auto-Detecting SATA 4...IDE Hard Disk
SATA 1: Sony DVD-Rom DDU1615S EYN1
Ultra DMA Mode-5
SATA 3: Samsung HD502IJ 1AA01109
Ultra DMA Mode-5, S.M.A.R.T. Capable and Status OK
SATA 2: ATAPI DVD A DH20A1S UX14
Ultra DMA Mode-5
SATA 4: Samsung HD502IJ 1AA01109
Ultra DMA Mode-5, S.M.A.R.T. Capable and Status OK
Auto-detecting USB Mass Storage...
00 USB Mass Storage Devices Found and Configured
No IDE Master H.D.D. Detected!
Chassis Intruded!
Fatal Error...System Halted."