gremlin
noun /ˈɡremlɪn/
  /ˈɡremlɪn/
- an imaginary creature that people blame when a machine suddenly stops working
- They blamed gremlins in the printer for the fact that the work was late.
 - What wrong with this program? Looks like the gremlins have been at work again!
 
Word Origin1940s: perhaps suggested by goblin.