Sorry to hear of your problems with both the Sony DVP-CX995V changer and Sony support. I am not a bit suprised. The problem you are having is not uncommon unfortunately. It can happen with the other Sony changers as well, namely the 985V, and 777ES. Losing disc information is one of the long standing issues with these changers. This will not be fixed with the current changers on the market, so I would not waste your time with Sony support.

The best thing you can do for yourself is to stop using the Disc Explorer interface. At the very least use an Excel spreadsheet to document what slot each disc resides in. Another alternative is to use an application called DVD Profiler. This is what I use to manage my DVD collection. As I add each disc to my DVD Profile it is assigned a collection ID. I then load said disc into my changer according to it's assigned collection ID's.

DVD Changer 01 (Slots 001-400) = DVD Profiler Collection ID's (0001-0400)
DVD Changer 02 (Slots 001-400) = DVD Profiler Collection ID's (0401-0800)
DVD Changer 03 (Slots 001-400) = DVD Profiler Collection ID's (0801-1200)
DVD Changer 04 (Slots 001-400) = DVD Profiler Collection ID's (1201-1600)

With the DVD Profiler application you can quickly order your entire DVD collection by Title or by Collection ID. You can also print out reports as simple or as elaborate as you want in case you would like to flip through a book for instance choosing a title versus having to use the DVD Profiler application. You can also apply filters to your collection displaying all movies under a given genre for instance, or displaying all movies which contain a certain actor or actress. It's a great program! I could not live without it.

If you do end up entering your collection in DVD Profiler there are several DVD management solutions out there which will allow you to import your DVD Profile. The couple I can think of right off hand are below.

1) DVDLobby by Cinemar.

Your Sony DVP-CX995V changer does not have a RS-232 port. As such you will need to go the IR route with DVDLobby. This means that in addition to a HTPC you will also need a USB-UIRT and Girder. I use both these to control my HTPC via my TSU7000. Works great!

2) DMX-3000 by tripleBsoftware.

This solution requires a MX-3000 remote control. The support thread here at RC for the DMX-3000 software can be found here.

I have my own DVD management solution as well for use with the ProntoNG line of remotes. (TSU3000, 3500, 7000, or 7500) If you happen to own one of these remotes it's as simple as downloading my configuration file, making any of the needed adjustments on the setup page under my DVD changer device/s, importing DVD cover images at 72x100, then linking each to the proper slot number. While this is a manual process it is certainly not rocket science. If you would like to learn more go here.