To fix the issue you can use one of the following:
- Run Regenerate Core on .xco source after adding it to the project.
- Run XST - Synthesis first and then change the project synthesis tool to Precision.
- Remove the .xco file from the project and add the .v or .vhd file in its place.
- Use VHDL as the intermediate language for IP cores as follows:
1. Select the core in the sources window.
2. Right-click on COREGen -> View HDL Functional Model in the process window.
3. Select properties.
This problem has been fixed in the latest 9.2i Service Pack available at:
http://www.xilinx.com/xlnx/xil_sw_updates_home.jspThe first service pack containing the fix is 9.2i Service Pack 1.