To address the issue of your number pad's "-" key locking your PC, it may be related to the Keyboard Filter feature in Windows. This feature can suppress certain key presses, and it might be configured to treat the "-" key as a lock command. You can check the Keyboard Filter settings to see if the key is being suppressed or if there are any custom key combinations set that might be causing this behavior.
As for the function keys requiring the "fn" button to work, this is often a setting in the BIOS or UEFI firmware of your device. You may need to access your BIOS/UEFI settings during the boot process and look for an option related to function key behavior, which can usually be toggled between standard function keys and multimedia keys.
If you are unable to resolve these issues through the settings, consider checking for any recent updates or drivers that may need to be installed, as glitches can sometimes be fixed with software updates.