It may not be a good to practice for sure but the MS model keybaord(usb with P@/2 adapter) has to be unplugged in order to use a standard 101 key model just to see the F8 key work at the license agreement when installing Windows an MS product!
Figure that one out!
I usually end up simply booting with the roll up vinyl keyboard plugged in until the first desktop is seen and plug the MS Media Pro Intellitype model plugged back in. If you are still able to see the post screen with or without the full screen logo enabled in the bios the black screen with flashing _underscore is simply from a drive set as the default boot device not having boot information or the drive is failing.
I've been into that on a few systems looked over lately where repair or full installs would freeze up and the primary could be removed while you couldn't create a new one. The replacement would see Windows go on with ease.