Are the DVD's you are putting in your computer made by you, or are they OEM? (From a company and most likely has a label on it.) Sometimes if you make the DVD yourself, there can be other issues that can make boot problems. If you can get your hands on a .iso file of Windows, then you can use Rufus to make a bootable USB flash drive and install it that way.
One reason why your computer might be taking a while to boot up is because it is searching for a bootable medium. You can configure this in your BIOS so that way your HDD is the first in order, but if you do that you will have to open up the boot menu to select the DVD/USB for your windows installation. You should also try re-setting you BIOS by disconnecting all power sources and removing the small battery that is on your motherboard. That has helped me many-a-times.
My question to you is, when you turn on you computer, can you hear the drive make noise at all, or does it remain silent?