You know, I haven't had too many good experiences with wireless keyboards or mice. I'd loose connection pretty often for both the keyboard and the mouse while playing Battlefield 1942, whenever I would use the scroll button on the mouse to switch weapons.. it would keep going like a roulette wheel.... by the time I would get it to the weapon I'd need.... I'd get fragged. O well.....
If your computer is having connectivity issues, try hitting the "connect" button that is usually on the bottom of the mouse/keyboard. That re-synchs the wireless devices to the usb wireless point. See the pic. for an example of what 2 look for.
Also, If you see that this keeps happening.. even after you go for the connect button, try switching the batteries for a pair of fresh ones. Tha could make the world of a difference!!
wireless keyboard is not responding at boot time 
Linear Mode
