We just got a new PC (Dell OptiPlex 7020) in which Device Manager says the drivers for the USB Controller are not installed (and its says "Code 28"). But the USB ports seem to work anyway (I have a keyboard and mouse plugged into them and they work). But I decided I should still try to fix this problem, but was unable to. It keeps saying "Windows could not find driver software for your device."
Then I noticed the BIOS was not current. So I updated the BIOS. Now when I boot up and get to the Ctrl+Alt+Del screen, the keyboard and mouse don't work; they're completely unresponsive. But they still work when I boot to "Safe Mode with Networking." I tried to undo the BIOS upgrade by removing the CMOS battery but I can't. The holder for that battery on the motherboard is designed to not let you remove the battery. In the BIOS settings I clicked the "Load Defaults" button, thinking that would undo it; it didn't.
How I can get the keyboard and mouse to work again?