You can also work around this error by manually editing the ".dia" file in a text editor as follows:
1. In the line that begins with "vetarget synopsis", change the reference to one of the following: "vetarget generic" "vetarget synplify" "vetarget xilinx"
Once the state diagram is opened, you can always change this option by selecting Options -> Configuration.
2. Select "Verilog" in the Language section, and select any available options under Language Vendor.
NOTE: DIA files created before the 6.1i release were encoded and cannot be edited as described above. In this case, you must replace the "sc.exe" executable in the "$XILINX\bin\nt directory" (Modified Nov 4, 2003) with the "sc.exe" file from a previous 6.1i installation. If a previous version of "sc.exe" is no longer on the system, you can request it from the Xilinx Hotline at: http://www.xilinx.com/support/techsup/tappinfo.htm
This method might also be more convenient if you have multiple ".dia" files.
Once the "sc.exe" file from ISE 6.1.03i is replaced with the "sc.exe" file from ISE 6.1i, 6.1.01i or 6.1.02i, the ".dia" (state machine) files saved in any version of StateCAD can be opened correctly.