Drive 3 not found: Serial ATA, SATA-3

Two days ago I bought and installed an ethernet card for my Dell 8400, Windows XP. An error page has come up since then, and I usually bypass it by pressing F1 to continue. Today I thought I would try to fix this problem by going into the optional setup window and change the optional drives all onto On. When this made the error message even longer so I changed everything back. The SATA Operation drive is set to RAID Autodetect/AHCI and Drive 3:SATA-3 (presently). After I played with this the computer won't even upload (continue startup process) after the Error page. What do I do??? (Other than tackle problems bigger than me) Thank you

I ran hard drive diagnostics and it said….. Drive 2: No device Drive 3: No device Drive 4: No device Drive 5: No device