Fred99:

sbiddle: 

Are you trying to use it as a primary keyboard? It's not designed for that and really is totally unsuitable.

Sometimes - yes - if it's the keyboard you've got in front of you, that tends to be the one you use.  I'm using it right now - browse the web etc no problems, but I'm not going to switch to a different keyboard because I decided to type a reply in this thread.
I had a full-sized logitech wireless keyboard which was much better, but not resistant to being eaten by a visiting dog.  I use the MK400 with the mouse from that combo - which works just fine with the "unifying" receiver.
Wireless keyboards used for "HTPC" type duty do tend to get a bit of a hard time, dropped, trodden on, spilled on etc.  I don't expect this one to last - although they seem to be quite well made for the price.  When it dies, I'll replace it with another full-sized keyboard sans-touchpad.