My MS wireless keyboard does not work when I first start the computer.  I have to start then restart to get it to work.  I have just installed a new Asus M3A78 pro mobo.  I did not find anything in bios to change.  The wireless receiver plugs into the ps2 socket and USB for the mouse, which works fine.  The keyboard worked with the old mobo, and a wired keyboard works on the first start.
I have:
win XP
Asus M3A78 Pro
AMD Athlon 64x2 4800+
Crucial 4GB ram
Pri HD WD 200 GB IDE
SATA HD 80 GB
Thanks in advance.Some many people have trouble with
wireless keyboard and mice that they just give it up.Things to check :
Batteries
Remove any other wireless devices from the area including cordless and cell phones.
Turn on "enable legacy USB devices" in the BIOS.
Re install the drivers for the wireless set since the MBoard has changed.Batteries are new.
There no other wireless devices in the area.
"enable legacy USB devices" in the BIOS is on 'auto'
Re installed the drivers for the wireless set.
Still the same. 
This doesn't work even in the bios until I restart(I think this what they call  a warm boot).
Probably because it is a USB device which doesn't kick in until Windows LOADS the USB drivers...
So if you need access before that invest in a PS2 keyboard and mouse combo...The mouse is USB, which works on the first start, but the keyboard is PS2.  It used to work even in the bios [on a cold boot](other m/b).Probably a stupid question but is the transmitter and receiver in the same place as it was before?

I bought a SIMILIAR MS wireless set up for my daughter it uses a ps2 CONNECTION for the keyboard and I use the usb for the mouse. She has had it for 2.5 years and I have only just today replaced the batteries but I also had to press the connect button on the bottom of the mouse. Maybe resetting the keyboard would do the same thing. LOOK on the bottom of the keyboard and press the connect button. Hope it helps.Yes there in the same place, only about 6" from the keyboard.  I've tried the connect button a lot.  I tried typing while it was booting to activate the green lights on the receiver but nothing works.  I can't get it to activate in
XP until I restart from XP.  Then it activates as normal.When all else fails, read the instructions!  I assumed the dual port receiver used both the USB and the PS2 plugs but when I tried a wired keyboard, I got two keyboards working at the same time.  When I left the PS2 unplugged it worked fine.  I guess that's what 'patio' was trying to tell me.
Thanks for the help!Well, I will give you a $1 for it
...if you include postage.Yep.
It was...