If you checkmarked "Waveform Wrapper" in the Essentials Pack,
make sure you also installed the Nullsoft Waveform Wrapper update after.
There's a link to it in the Updates
section of the first post, under the Essentials Pack.
There was a bug in v1.0 which caused high cpu-usage, lockups, or no startup when the playlist was empty, which is fixed in v1.01