Hello j n
What you are describing is impossible! An AOLAP workspace cannot "lose" it's layout. When you first create an AOLAP workspace it uses the default layout as defined in the BEx Query... but from that point on the workspace is largely decoupled from the Query. Think of the AOLAP workspace as being like a Query View. AOLAP has no concept of reverting to a default layout.... and yet it appears to be happening.
With that in mind there are several things to consider...
1) Are the AOLAP workspaces being opened/saved using the BI Launchpad or via a portal with iViews?
2) When the AOLAP workspace is saved, is it being saved where the user expects it to be saved (ie if they go to the Documents tab in the BI Launchpad can they navigate to where they saved their workspace, open it and confirm that it was indeed saved)?
3) Is there any backup/restore taking place where content is being restored with older versions?
4) When a workspace resets to the default layout, what is the date/time stamp on the workspace? Does it correlate to when the user last saved the workspace?
5) Is it ever possible that a user has rights to save a workspace to a particular folder at some times but not other times?
6) Are the complaints typically from the same users and on the same dates? Are there other users with similar work patterns who have never had a problem?
I hope these provide some areas of exploration.
Kind Regards