Dear Rich,
thank you very much for the prompt reply. The point is, that Windows 7 users on the machines in question are not supposed to know the XPMUser password. The Windows 7 machines in question run in rather restricted mode in which restricted windows 7 user is only allowed to run just one virtual application.
Perhaps the solution could be to automate the Windows Vault backup and recovery, but that is unfortunately beyond my competence.
In any case I find it not normal that in Windows Vault saved credentials are lost when the user changes her/his logon password in a very standard way.
Best regards
Antanas