Problem: PC/FPGA communication is not working.
Solution 1: Make sure you have a valid UCF (Xilinx constraints file) and have included it in your project. Otherwise, the pin mappings will not work correctly and the FrontPanel host interface will not be visible from the PC.
Problem: Configuration and pipes are not working with Windows 2000.
Solution 1: Try disabling Asynchronous transfers. With the API, use the method EnableAsynchronousTransfers. With the FrontPanel Application, you can disable them from the Preferences… dialog under the FrontPanel menu.
This appears to be a driver issue with some host controllers. In some cases, once you tried a transfer with asynchronous transfers, you will need to detach and power off the XEM device.