Audition CS5.5 deleting files from "Recorded" subfolder on closure

Question

Hi
I use Audition CS 5.5 version 4.0 Build 1815 on a 32bit XP Pro box using a 1TB raid 1 array on 2 identical drives.
Yesterday I worked on 2 seperate projects previously created and saved. Using the multitrack editor with 2 tracks of music, and one of multiple instances of live voice recorded whilst I worked, which were saved in the "Recorded" subfolder by the program as (eg) Track 4_003.wav and .pkf files..
After assembling the music and voice tracks with fades etc as normal, and saving regularly whilst working, at the end of the session I checked all the music/speech junctions then saved and exited.
Today I came to continue working on these projects to find that Audition appears to have deleted around half of the files, some 16 pairs of .wav and .pkf files, from the Recorded folder, starting from Track 4_001.  All the deleted files were recorded prior to yesterday.
This has occurred in both projects which are on seperate parts of the raid array.  The session files expect to find them, and cannot, of course.
The files are not in the recycle bin and there was no evidence of them on the raid array when scanned with GetDataBack, even as deleted files. It is as though they never existed.
This is very alarming, not to say extremely inconvenient, as a whole day's work has gone down the drain.  It would appear to be Audition causing the problem as the files were definitely in the recorded subfolders prior to closing the projects, and now they aren't.  I have never known XP, much as I hate the OS, to selectively delete sequential files from a folder.
Is this something that is known about Audition, and if so, is there a solution short of making a seperate backup of everything in another location prior to saving and closing Audition?
I'd appreciate any input on this before I grovel to the voiceover artist.
Christopher

Answer 1

It is very strange, and as to why they don't appear on a whole disk recovery scan I have no idea.  They were definitely on the raid array at one point, I checked the folder contents outside of AA, and they are still logged as having been created and on the timelines in both the .sesx files. 
If AA had overwritten them then the file numbers would have been reused, but both projects have "lost" all the lower numbered files, starting now at 16 & 17 respectively, AA hasn't reused the numbers. The chances of new numbers actually occupying the same disk sectors is very remote.
The only thing I can check is the operation of the "cut" & "delete"  commands in the multitrack editor.  There is the possibility, which I have to check, that, having split a recorded voice take up into seperate clips for use at various point on the timeline , when asked to cut or delete a split clip AA actually deletes the whole clip, not just the split section.
I have set up a test session and will try this out to see if AA automatically renumbers split sections. I will report back later.
Christopher