Inactive screen saver

Please could you help.
Since installing a new Microsoft Wireless Optical Desktop 1000 to the USB port of my computer, which is running Microsoft Windows XP Home. my screen saver will not activate.
I have tried to resolve by connecting the new wireless receiver to a PS2 port, using a USB adaptor, but this will not allow the mouse or keyboard to function.
Any suggestions to resolve this?
Many thanks and kind regards,
Malcolm.