If you experience any problem downloading, installing, or using Ciao you can send a message to <ciao-bug@cliplab.org>. Please be as informative as possible in your messages, so that we can reproduce the bug.
This is a list of common issues and their solutions:
Possible reason and solution: It is a good idea to clean up any leftovers from the previous compilation. It the worst case, if none of the clean commands work, try ./ciao-boot.sh emergency-clean.