After a lot of boring and unnecessary work, I have localized what causes the Unused Block warning in my Logic song. It is the number of X-fades in the song that somehow triggers this problem. At least for me. This is what I did - First, I deleted all Arrange regions (first I did this whole procedure deleting automation, but the second time I kept automation and it still worked), all files in the Audio window, and the whole Undo History. - Then I saved the song as a template and closed it without saving. - I created a new song, using this template, thus getting all channel setting and automation back. - I opened the old song again, without closing the new one. Between each following step I tried playing, to rebuild fades, saving and reorganizing memory: - I copied the tempo track to the new song. No warning. - I created a short silent audio region at the start of the song on each track that contained information I wanted to copy to the new song (= all). - Now, I started copying the files/regions to the new document. First I tried copying all at once but then the Unused Block warning appeared. I chose undo and started copying files/regions a few tracks at a time (Ctrl-selecting a few tracks). - The last tracks I copied were the 18 or so drum tracks. The warning came back. - I tried removing all fades. Warning disappeared. Aha. - I went back a step and just removed the drum fades. Warning still disappeared. - At this point I was certain there was a corrupt fade file (or rather, since the fade files are rebuilt, a corrupt file that could not be faded or something), and so I started putting fades back drum track by drum track. Every track contains some 50 or so fades, X-fades of 4-9 mostly. - Suddenly on the bottom snare track, the warning came back when reorganizing. I took the fades on that track away and it worked again. Aha. Thought I. - I noticed that all remaining drum tracks seemed to generate the same warning, so the snare file might be OK after all. - I removed the fades of the first drum track that I put fades back to (and that I thus knew worked fine with fades) and put fades on the snare track instead. Worked fine. Hence, I come to the conclusion that it is the TOTAL NUMBER of fades that trigger the Unused Block warning, or possibly the total number of Events in MIDI Regions that can be seen in the Song Information? I just tried a thing that had a weird result. I put X-fades on another drum track to generate the warning during reorganize memory. Then I exchanged all X-fades on one track to Out-fades, and the warning disappeared. Anyone, please come with any ideas and/or suggestions as to what this might be...? Cheers, Daniel