bugaboo

(bŭgˈə-bo͞oˌ)

1. An object of obsessive, usually exaggerated fear or anxiety: “Boredom, laziness and failure . . . These bugaboos, magnified by imagination, keep [the workaholic] running” (Dun's Review).
2. A recurring or persistent problem: “the bugaboos that have plagued vision systems: high price and slow throughput” (Lawrence A. Goshorn).