Thanks to wabe's response I've solved my problem. The .prv file is the culprit, but also the way around the problem. If I forget to put in the right disk in time and get the Empty Collections notice, I just insert the CD and erase the .prv file before I try loading the collection again. Vue then re-builds a new .prv file and everything is golden. This may also explain why gebe finds using a library so slow. Sams3d and gracia's collections have got to be huge. They have generated so much good stuff. If Vue has to rebuild .prv files for them it has to take forever. Since I am bad with names, particularly when other people make up the file names, I'll try an keep building my own CD libraries, but will subdivide each collection so that the .prv rebuilds don't get too large.