Strange problems with prrinter

I am trying to help a friend with her computer. Here is the situation. There are 2 laptops both running xp. They are connected to the internet via cable and router. The router is wireless and 1 laptop has the cable running directly in and the other laptop has a wireless card. They are both connectd to the printer, 1 via usb cable and 1 via parallel cable. I think have describe the setup accurately. Here is the problem. If laptop #1 (the one with the wireless card and the usb printer hookup) is connectd to the printer, laptop #2 (the one with the direct cable and the parallel printer hookup) cannot type with the keyboard. If laptop #1 is unhooked from the printer and the printer is turned off and back on again, the laptop #2 can type. This is the strngest thing I have ever seen - well, maybe not the strangest, but definitely right up there. Does anyone have a suggestion on how to correct this?

 

Thanks for the suggestion. Both computers are able to print. What could be causing the keyboard problem? Also forgot to mention that just prior to the keyboard not responding, the cursor starts to get circles or halos around it. Sometimes the keyboard will work, but not type the keys that are hit. For example if I type a "J ", what appears is "M ". Strange. If laptop #1 has been using the printer, not only does it have to be unplugged from the printer, but the printer also has to be turned on and off again before laptop #2 can use the keyboard. If you still think an a/b switch is the answer, please tell me how it would be hooked up. Thanks.