I am not sure when it happens since I am not the only one in the house that uses the Rio. I do not think it is related to use though. Never had a problem with modems but I don't use it as much since I have a cable connection. I have tried removing...reseeding the card and have even put it in another pci slot. Right now the card is recognized by the OS but it says it cannot start (code 10). I have tried reinstalling the driver with no help. This is a 3com HPNA card. I have noticed they no longer make this product. It was real cheap when I purchased it. I have seen them selling for about $10 online. Other cards are about $40. Is it something with this particular card???