Can I open Lightroom without upgrading my catalog?

Question

Unfortunately I'm not sure how to do a screen capture, so I'll try to type what I'm seeing.
When I click on the LIghtroom icon, I get a message box that says "Please upgrade the catalog file "Lightroom Catalog 3" for use with Lightroom 3.  It continues "Lightroom will create a new catalog file in the destination indicated below.  The previews will also be moved to the location and converted for use in Lightroom 3"  Upgrade destination C:/Documents and Settings/...../Lightroom 3 Catalog-7.lrcat
There is a button to choose a different catalog, upgrade or exit.
When I open the button to change catalogs, it gives me one option, but when I click on it, I go back to the "Lightroom will create a new catalog"
My concern with upgrading is that I've a workflow for the catalog that's at C:/Documents and Settings/..../Lightroom 3 Catalog-5.lrcat  Earlier today, I clicked on the dialog that resulted in a catalog at Lightroom Catalog-6.lrcat, but when I opened it, I'd lost all the listings for the Free Agent drive (usually G:/ where I do my daily uploads.  I could still see the external hard drive (E:) where I save edited work, but it indicated that I would have to locate all of the folders I'd created on the E: drive.  I saw only the default collections on the left hand side -- (smart collections, last month, etc.).
I finally was able to get back to Lightroom 3 Catalog-5, which had all the work, but I'm not sure how to recover all my collections and folders if I Lightroom creates a new catalog at a destination that has a different number.  The problem is that now I can't seem to open Lightroom 3 at all -- when I click on Change, I don't see my catalog 5  in the default folder.  I know I found it once before, and it became an option on the pulldown menu.  But I don't want to have to keep finding it on the drive where I store it so I can keep my indexing and folder and catalog organization. 
Lightroom 3 Catalog 5.lrcat works fine for me.  My default for backing up is whenever I close the program, so I'm confident in it's integrity.  How can I open Lightroom with the catalog that works for me --without getting messages that seem to force me to do an upgrade I don't want to do.
Thanks for your help!

Answer 1

I've been using Lightroom 3 for about a year.    Right now I'm going
back to the folder with my backups and opening Lightroom 3 Catalog-5.  I
think I've tried to reconstruct my left side panel with earlier
Lightroom 3 Catalog x versions.  I don't have all the collections and
folders I had with my Lightroom 2 catalog.    That catalog seemed to
have been corrupt when I moved to Lightroom 3.  I don't recall how I did
it, but I guess I imported the photos and tried to start over with my
collections.
Jan