The Collaborative International Dictionary of English v.0.48:

Flaky \Flak"y\, a.
   1. Consisting of flakes or of small, loose masses; lying, or
      cleaving off, in flakes or layers; flakelike.
      [1913 Webster]

            What showers of mortal hail, what flaky fires!
                                                  --Watts.
      [1913 Webster]

            A flaky weight of winter's purest snows.
                                                  --Wordsworth.
      [1913 Webster]

   2. prone to strange or erratic behavior; -- of persons.
      [PJC]

   3. odd, unpredictable or unconventional; offbeat; whacky; --
      of behavior.
      [PJC]

   4. unpredictable, erratic, or unreliable; -- of machinery,
      especially electronic devices. "a flaky computer board."
      [PJC]

WordNet (r) 3.0 (2006):

flaky
    adj 1: made of or resembling flakes; "flaky soap" [syn: flaky,
           flakey]
    2: made of or easily forming flakes [syn: flaky, flakey]
    3: conspicuously or grossly unconventional or unusual;
       "restaurants of bizarre design--one like a hat, another like
       a rabbit"; "famed for his eccentric spelling"; "a freakish
       combination of styles"; "his off-the-wall antics"; "the
       outlandish clothes of teenagers"; "outre and affected stage
       antics" [syn: bizarre, eccentric, freakish, freaky,
       flaky, flakey, gonzo, off-the-wall, outlandish,
       outre]

The Free On-line Dictionary of Computing (19 January 2023):

flaky

   (Or "flakey") Subject to frequent lossage.  This use is of
   course related to the common slang use of the word to describe
   a person as eccentric, crazy, or just unreliable.  A system
   that is flaky is working, sort of - enough that you are
   tempted to try to use it - but fails frequently enough that
   the odds in favour of finishing what you start are low.
   Commonwealth hackish prefers dodgy.

   [Jargon File]

   (1996-01-05)


The Jargon File (version 4.4.7, 29 Dec 2003):

flaky
 adj.

    (var sp. flakey) Subject to frequent lossage. This use is of course
    related to the common slang use of the word to describe a person as
    eccentric, crazy, or just unreliable. A system that is flaky is working,
    sort of — enough that you are tempted to try to use it — but fails
    frequently enough that the odds in favor of finishing what you start are
    low. Commonwealth hackish prefers dodgy or wonky.