The application ran your source text through the Inform 7 compiler, as usual, but the compiler unexpectedly halted with a fatal error.
Fatal errors are usually the result of a problem with the file-system, but it is unlikely that your computer is at fault. More likely causes are:
However, if you think it more likely that the Inform 7 compiler is at fault, please check that you have the currently distributed build of the system: if you have, please consider taking the time to fill out a bug report form and email it to the author.