Ctrl F11 on Dell 8400 doesn’t work,

I got a blue screen and so was going to use the utility disk to reinstall windows as on older computers it didn’t work. There seems to be 3 partitions I’ve since figured out. I tried the Ctrl F11 and it doesn’t work. I now get a message that windows\system32\config\system is missing. Can I just delete all the partitions and use a home version of Windows XP and start from scratch.

Or is there a better route, one that would keep the partitions yet get me back to what the computer was when I bought it.

Thanks