Well first make sure the batteries in the wireless keyboard have enough power.
Also, because it is a wireless keyboard, there is possibly an issue with latency, ie how much time it takes for a packet of data (a series of keystrokes) to get from one designated point to another.
The wireless medium itself introduces some delay. The size of the packet introduces delay in a
round trip since a larger packet will take longer to receive and return
than a short one.
My point is there is already the wireless medium to consider. If you then couple that with the settings to which the keyboard is configured (In keyboard, in Control Panel, or maybe the software that was installed from the disk that came with the mouse/keyboard), eg Keystroke repeat rate, keystroke repeat delay etc. then the process has a capacity to falter.
I would put the Repeat Delay for the keyboard at about 2/3's and experiment with the Repeat Rate in case that makes a difference.
As for setting it as the 'default' keyboard, I'm not exactly sure about whether that would make a difference, and I also don't know if it is possible to set it that the laptop 'completely ignores' the original keyboard, as I'm sure the CMOS needs to detect a keyboard on bootup, in order to proceed. USB/wireless keyboards, I imagine, are 'loaded' after this point, so if you actually 'disabled' the original keyboard (in order to stop it possibly causing error), there is a chance that the laptop would not boot in the first place. This is just a theory of mine, however..
I would play with the sensitivity (keyboard repeat rate and delay) and make sure your batteries are juiced up.
I guess you could scan, fix and immunize with Spybot
, just in case there is a malware issue there too.. Just a remote possibility..
I actually have a wireless Belkin keyboard and mouse somewhere, I'll look them out and check the software configs, and see if I can give you any more ideas. The software that came with the keyboard and mouse would be the place to start, to make them 'sort of default', in the sense that system resources would be more prioritised in their favour. Have a look in that software, and I will do the same and post here if I come across anything.
Hope this helps
ps sorry about the technobabble ;D