Microsoft Keyboard Shortcut Delays

I have a Microsoft Wireless Comfort Keyboard 5000 and every so often when I try to use of the the quick launch keys, I get a huge delay before the program actually launches. Other times, it will launch instantly. This is any program from the assignable quick launch keys to the built in calculator button.
Any idea what I should check for or what the problem might be?

Thanks,
Toby

Does the delay still happen when you have been logged in for a while? I get a huge delay between logging in and Windows responding to shortcut keys (e.g. Ctrl-Alt-B). Double-clicking the same shortcut launches the program instantly.