I am trying to identify a short story read in the 70's about a future world where humans are reliant on computers that control everything, including food delivery. One day the system dies and the central character (woman?) cannot even move to find sustenance as she has become much like a giant slug from years of inactivity.

Not Bradbury. Posted to the usual places; we'll see what they come up with.

Rocambole at the BookSleuth forum at Abebooks and Dreamer at the rec.arts.books.childrens forum at Google Groups both suggested E. M. Forster's "The Machine Stops." The details don't seem to match perfectly but it is online here: http://www.plexus.org/forster/index.html for purposes of elimination, or for anyone interested in a story with a similar subject.