no keyboard and mouse at login screen

Powered up computer following day (worked fine) and the keyboard and mouse dont work at the login screen. The numlock key is lit but stuck. However the computer is not frozen because the cursor in the password field is blinking and if I press the power button, the screen changes and it does a proper shutdown. Right now I'm booted into safe mode with networking and the keyboard and mouse works fine. The keyboard also works in the bios. I tried booting with the install disc and doing a repair and it said it did something but it was not corrected. I also tried plugging in a different keyboard with the same results. Any ideas for troubleshooting would be appreciated.

while writing this post i got the idea to plug into the extra keyboard before i boot. I tried this and it allows either keyboard to work!? Then I login and it takes about 3 minutes which is very odd. The majority of the time it sits at a black screen with the mouse in the center and you cant move it but the numlock key on the keyboards works. Finally it recovers and appears to operate normally. I tried to reboot without the extra keyboard and the problem returned. I'm writing this post from normal bootup on the standard keyboard (I unplugged the other keyboard after logging in). What the heck is going on?

If you have two keyboards plugged in a the same time you are confusing Windows.

I did this only for troubleshooting. The problem happened before adding a 2nd keyboard.

Where are you plugging in the keyboards?

The original keyboard is in the rear USB port. The additional keyboard is in the front USB port.

What keyboards are you using?

Dell and Amazon. I don't see model numbers. Both USB.

sfc /scannow from admin cmd prompt yielded

Windows Resource Protection did not find any integrity violations.

Also use this tutorial by Brink to fill in your system specs. We need to know what we are working with.

done.

both keyboards work in another computer when plugged in at bootup and hotplug while running. I tried booting the trouble machine without either keyboard and had no problems. Then I re-tried it with the original setup that had the repeatable problem...it works now. I don't like fixes I don't understand but now I can't recreate the problem.

I don't know how, that's sort of the point. I performed the steps you requested above and in the process I realized the symptoms were no longer there. It has been some time since I posted the original problem so I can't be sure the problem had not resolved itself before today.