Another 3.4.1 disaster or my mistake?

I am relatively new to Aperture (few months) and recently did the upgrade to 3.4.1 as requested by the program.

I have the Vault feature active on an external hard drive and regular backups on another internal drive.

In brief, I tried to import photos and "suddenly" many of my recent photos and albums were no longer in the Library (folders, projects, Smart Albums, etc.). I'm sure that I did nothing different during the attempted import. I tried the restore function with the Vault but it "hung up" after getting almost to the end of the process - no success. I haven't cone anything else so far for fear of losing more stuff...

1. Is this another problem with 3.4.1?

2. Can I just open the Vault file and remove/extract/retrieve the missing stuff I want? (or is it in some sort of compressed, "don't mess" format?)

Suggestions welcomed!

KWO