PCI is the bus that the computer chip uses to communicate with virtually all the devices and subsystems connected to your motherboard. Not knowing the exact message you are getting, it would seem that one of these devices is not working properly.
Start the Device Manager (Start -> Run -> "devmgmt.msc") and it will indicate which device is not working properly with either a red "X" or a yellow exclamation mark.
HTH,
JW