Avid Pro Audio Community - HELP!! regions disappear in bin

Grrrrrrrrrrrrr!!! Someone please help. Okay, in the edit window, in the region list on the right...occasionally, regions that I've created disappear from the list, if unused. For example: when I drag that region of audio into a track, then later I decide that I don't want that region there or need to replace it with another, and I clear it out by hitting the backspace/delete key or apple-b (not actually deleting it, so that it still exists on the hard drive) this is when it disappears from the list. (It only disappears if it hasn't yet been used.)
In my case I'll take an audio file of room tone and cut it into smaller regions of varying lengths to edit dialogue with. I always export the region definitions (both ways) so that I can always re-import them when this happens.

I have had this happen on every computer I've ever owned from my 9500, G3,G4, and G5, as well as every Pro Tools hardware/software from 4.3 Mix Plus, all LE platforms, to HD 7+.

It's not a major "problem" per say, but annoying as hell! Any thoughts????