Wireless keyboard and mouse

[weamish]

I'm trying out the MS Wireless Laser Desktop 4000, having several problems (none of which are present when using a wired keyboard and mouse) -

...The middle button operation is set to middle click for Firefox. It's very erratic - sometimes it works, other times nothing happens.

...The Sleep function is erratic.

...Getting screen flickering in some programs.

...NumLock behavior also erratic - it's set to Off, but keyboard shortcuts like CTRL-HOME often don't work.

Any ideas? Thanks!

Steve