Labtec ultra flat wireless desktop usb mouse &...

hi, i just recently got this wireless keyboard and mouse, but when i plug the receiver into the usb port, i click the connect button and the connect buttons under the keyboard and mouse, wait, and nothing works. I have replaced the batteries countless times, and this makes no difference. i also tried it on a friends laptop, but it worked on his, but not on mine. if you could help solve this, i would be very grateful

also i have windows xp, so i thought it should work, and have also restarted the computer and taken the original mouse and keyboard out