Hello, and thank you for using this service.
Which windows are you running?
Windows XP, 7, 8, or 10?
32 or 64 bit?
I can call you, but there is an additional fee for that service. Also, it would be helpful for you and me to get some further information.
Have you had your K800 keyboard and/or the MX Performance mouse working previously on this system? If not, have you purchased one of the items recently, and previously had the other installed and working?
Please tell me the following:
1) Do you have two unifying receivers now? One you got with the mouse, and one with the keyboard?
2) If you look closely at the receiver(s), there might be a thin colored band around the top of one or both. Tell me about that and which one came with which device.
3) If you have two receivers, Have you tried plugging both of them in, or one of them at a time , to see if you can get the devices working?
Have you tried using one receiver to connect to one device (not both at the same time)?
If not, please do this. We need to make sure we have a working receiver to unify with. Logitech has been known to send out faulty receivers, so this is a way we can start to diagnoses your receivers.
Just shut down your computer. Plug in just one unifying receiver, and then plug in your mouse. If that works, shut down or restart again and while computer is shutting down , move the receiver to a different USB port, and also turn off your mouse (or remove a battery). Turn on your keyboard. Verify it works. Let me know the result of this test. Thanks.
Is the logitech software telling you there are "3 installations"? Did you install that from a CD or download?
If so, please unplug all receivers. Then, go to your programs/features, and uninstall the logitech software. Then, shut down and repeat the previous steps again. You shouldn't need the extra software just to make things work. You may need it to unify, but first let's get one receiver working with both devices (one at a time).