When I import an existing .xco file, I get this error in CORE Generator:
ERROR:coreutil:574 - Unable to set working directory to XX/coregen.cgc/
This error is being issued incorrectly in some cases. The IP core is imported correctly and the error should not be issued.
To avoid the error message, copy the .xco into the project directory and re-generate in batch mode.
This issue is fixed in ISE Design Suite 14.3.