network card failed to respond

dear all,

i encounter this problem twice already....whenever i have prolonged connection to the broadband ISP, say over 24 hours, my network card will fail to respond (no light "ON" on both network card and the "LINK" of ADSL modem) i checked the "hardware device manager" and it says the NIC is working properly. however, the "Network Connection" of WinXP detects that "cable is unplugged" which is not the case. I further checked the PC "BIOS SETUP" and found out the PCI slot which that "failed" card is installed was showing "GREY" - i.e. no config could be made to that slot.
the card is "Practical Peripherals" with REALTEK 8319 chip
and the motherboard is Intel D815EEAA.

kindly please advise what is going wrong judging from the info i've provided.

thanks a lot.

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