I watched this movie a a young child, perhaps 4-6 years old. I was born in 1994, so the movie must have come out before 2000. The movie stars a young boy in a strange land. In one of the scenes he is being chases and taunted by a small black creature that even summoned musical notes to crash around the kid.
However, the creature is more mischievous than malicious, as I remember he was among the many friends that came in the end to help the kid defeat the actual villain.
Visually I remember the creature looking remarkabley similar to the shadow heartless in the video game series Kingdom Hearts.
Two possible movies that have been brought to my attention are Little Nemo In Slumberland, and The last Unicorn. Although they are around the right time period and have a similar story, I could not find any of the scenes I remember in those movies.
The movie was animated in color and was in english.