My landlady brought me a P4 (1.4GHz) PC that will not boot up.The BIOS does not recognise the FDD.I've tested the PC with 2 working FDD's & 2 sets of cables.These work in my machine,but not in her's. I have the cables setup properly as to pin alignment and the twist is at the FDD.Any help would be appreciated.I'm thinking perhaps the IDE controller on the MOBO is going bad.

Make sure the floppy controller is enabled in cmos/bios setup. Make sure the floppy drive is properly identified as 1.44. Did she do a bios upgrade on it by chance? I've noticed a bad upgrade will often screw up the floppy access.

The floppy drive probably must be before the CD drive in the boot order in the bios Setup. In all computer bioses I know of, if a CD drive is listed in that, if the floppy drive is after the CD drive in that list, the floppy drive works in Windows but a bootable floppy will not be recognized while booting. Why is that? When a CD drive is listed in that list, when the bios gets to and uses that selection a virtual floppy drive is loaded at the same time while booting, even if there is no bootable CD in a drive, or even if there is a bootable CD and you choose not to boot it. I suspect the virtual floppy drive isn't unloaded immediately afterward if you don't boot a CD, and when that's still loaded the bootabilty of a floppy in the floppy drive can't be recognized. Less likely... Faulty computer power supplies are common. Check the current voltages in the bios Setup pages - if the +5v reading is more than 10% lower than 5v (< 4.5v) ,the USB, firewire, floppy drive, and CD drive are a lot more likely to not work properly. If she did do a bios upgrade, load bios defaults in Setup - otherwise the cmos may have a mixture of settings from the old and new bios version and the bios may not work properly.

"I'm thinking perhaps the IDE controller on the MOBO is going bad." I don't know if this has anything to do with the problem, but the floppy controller is not IDE. It has it's own controller, separate from the hard/optical drives.