brittle
adj. Said of software that is functional but easily broken
by changes in operating environment or configuration, or by any
minor tweak to the software itself. Also, any system that
responds inappropriately and disastrously to expected external
stimuli; e.g., a file system that is usually totally scrambled by a
power failure is said to be brittle. This term is often used to
describe the results of a research effort that were never intended
to be robust, but it can be applied to commercially developed
software, which displays the quality far more often than it ought
to. Oppose
robust.