Have a look at your keyboard. Somewhere in the user's manual or on the back of the keyboard on a sticker, it will tell you what frequency or band the keyboard is using for the radio transmissions between the keyboard and the computer interface.

If the keyboard is listed as using the 2.4 GHz unlicensed spectrum, (and I'm betting that it is) then you could have interference from wireless phones, headsets, WiFi bridges, you name it. that 2.4 Gig unlicensed spectrum is getting crowded with all manner of devices these days. Once these wireless devices lose their syncronization in their link-level protocol, you often have to "restart" the device and the receiver again to achieve synchronization. This would entail taking the batteries out of the keyboard and putting them back in, or rebooting/restarting the receiver connected to your computer by pulling the USB cable out and putting it back in.

There are other keyboards that 2.4 GHz -- these are using "Bluetooth" wireless interfaces. Bluetooth is notorious for causing all manner of 2.4 GHz interference, because unlike 802.11b wireless bridges/routers, Bluetooth uses the whole 2.4 GHz band.

If you have lots of wireless devices in your home, you might want to migrate some of them off to the 5.8 GHz band -- there are wireless phones that now use this band, as well as the 802.11a wireless bridges. Here, I got so tired of the interference between a 2.4 GHz phone and the wireless router that we bought some Panasonic 5.8 Ghz phones and haven't has a problem since.