When I double-click on an ".ncd" file in Windows, the file does not open. FPGA Editor opens, but it does not bring up my design. I receive the message:
"Open design /dde ERROR:FPGAEditor:5 - Unable to read file "/dde.ncd". Check path name and file permissions."
To work around this problem, simply open FPGA Editor stand-alone, and use the File->Open command to bring up the design.
This will be fixed in the next major software release.