No brother, unfortunately no further improvement here. I have a little idea but i don't wanna brick your machine.
It didn't work, when i boot with the CD it show me "Starting Caldera DR-DOS" And nothing, perhaps there is something worong with the burn.
Looks like cause i have tested it on my machine just now and it works here. Try making bootable USB again. And do this. Once USB is created click on the little icon in the system tray to "safely remove" it and remove that USB. Then re-insert it again and your computer will probably say "new device is found". Then click that little "safely remove" icon again choose "remove"+"ok" but do not remove the USB stick - leave it there. Now reboot. This might help you to boot into DOS. EDIT: What are you burning it with? I'm using UltraISO here. So maybe try using the same. You can download a trial.
It use nothing, i juste click on your file and windows say me "burn on ..." I will try to use your softafe but i have tryed again the USB Boot No, it diddn't work after that, when i reboot i push F9 in order to choose where i boot, i select APTI for the USB but it launch me Windows 7.. Edit: Damn it i think i don't have CD anymore !
Well, then there is something wrong with that USB you made. Play with it, search online, maybe you'll find some other ways of making a bootable USB. Are you using disposable CDs? Mine are rewritable EDIT: BTW the only way i could boot in DOS using USB on my machine was when i made it following the instructions I have given you link for before.