I finally solved the problem on my own:
It appears that whether on opening and/or closing sessions, either PT or win or mac corrupt sometimes the "wave cache" file. I saw it on my previous systeme based on a G5-PPC, a friend of mine had similar behaviour with its G5-intel. I can't figure out if it comes from PT and/or OS file system. Disk management might be invoked too...
From years in such situation, I used to trash down the file, which was properly regenerated at a new opening, so did I repeatidly this time too. But it looks like "wave cache" contains critical infos now. They are definetely corrupted when it wheights 1ko in place of 100ko or more.
The solution is to look after the last correct wave cache and use it with the session backup file having exactly the same date/hour for a successful launch. Chance was I had trashed them...
From now on, I'll make sure to copy the good last wave cache file into the backup folder. Otherwise I have no idea on what to do to prevent such corruption...
