That happened because you created the catalog in a computer using Firebird 2.5.x standalone server instead of the version embedded in any copy of VVV. VVV uses 2.0.x.
If you are using windows you can update the server embedded in your copy of VVV, then the program should be able to open the catalog. Here are the instructions.
- download Firebird 32 bit embedded from here...
You cannot expect users to remember to save their work before leaving the program. Moreover you shouldn't keep a transaction open for a very long time.
Again, I think that the "Edit/Delete" menu should be enough to remove unwanted volumes from the catalog. Isn't it?.