Thanks for the PM.
What works was something like what you siad. The objective is to get Widowsd to see a hard drive on a SATA port and connected to the bujil-in stuff.
This Dell 755 has two SATA ports and a floppy connector. And lots of USB ports. But Windows 7 refuses to install no a hard drive on the any USB port.
He is what works. Remove the DVD drive and make it extrernal with an eternal PSU and a USB / SATA adapter. Th BIOS has not problem booting from an external DVD drive on a USB port. The legal Windows 7 install DVD sits there.
In BIOS disable the SATA 0 device, but leave it connected. Bow connect a second SATA Hard Drive to SATA-1 and make sure it is enable in BIOS.
Now when the Windows 7 DVD is booted, it only sees the seconddrive as the only drive. The first drive is physically present, but not enabled. So at last I have a new install of Windows 7 on a clean hard drive. No I can do the test I need to do to see why I can not install a specific program .
So that was the answer. Just make the DVD drive the external drive. How simple!
Thanks for yur help.