My hard drive is getting full and I thought I would start putting downloads on my CD-R/W instead. Vue provides a capability for this called Virtual Collections. Im hoping someone has been more successful than I was at doing it.

Here is what I have tried so far:
Ive added lots of collections on my hard drive before, so I didnt expect any problems. (Ha!) The first thing was to add a new collection and using the browser, point it to a directory on the CD. This worked fine till I tried it again but forgot to put the CD in the drive first. It came back with an Empty Collection indication. This made sense, but when I put the disk in it didnt change. I canceled the load object screen and tried again. No joy. The only way I could access the collection again was to exit Vue and restarted it. (Bummer)

Then I tried mimicking how the Vue Virtual Collections were done. I copied the working .prv file from the CD and put it in its own directory on my hard drive. I then added a new collection pointing to this hard drive directory. Opening this collection always indicates Empty Collection. (Double Bummer)

Can this be done or is it just a feature that e-on can use?

You can try the following. Install a fresh copy of Vue somewhere (standard installation) and see then how there the collections are done. And then copy this structure - if possible. When you have such a fresh installation not all the optional objects are loaded to your hard disk, you can do that when you need it. And when i remember it right, you can decide wether the object should be copied to your hard disk as well or not. I think the big problem is, that Vue tries to write back information to the .prv file when it realises a change (can't find the files in this case here). And because it can't find the prv-file as well it is confused and maybe creates a new, emty one temporarily. Only a guess. You should report that to E-on. But to be honest, my feeling is that this will be a very low-important issue to them. Not many users will have such a specific construction.Especially in times of very cheap hard disks. Broken down to the price per MB your way is probably the more expensive solution anyway. But thats a theoretical answer - don't listen to it.

I never could do what you try to do. I also have lots of vob files on CDs, by collections like "gracia" or Sams3d" but I use them differently and don't try anymore to put them in my library. I just introduce the CD when needed and select the file from there. As the files have names, I just need to click on it and it will show up a small preview. But if I try to put it in the library, Vue goes so extremely slow to search the files from the CD that I gave up.

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.