I have a problem with some of the cubes I administrate. The setup is as
follows:

The users access a virtual cube that performs the access control to the
underlying cube. The users sometimes lose their access to the cube and to
re-establish the access I have to process the virtual cube. The users tell me
that their access disappears when a user without permission to access the
virtual cube tries to access it. I have tried to test this scenario but I
haven't succeeded in "corrupted" the virtual cube.

The cuberole is defined with the following MDX statement:

STRTOSET(IIF(USERNAME="","{}",SETTOSTR(GENERATE(NO NEMPTYCROSSJOIN([Shortdiv].[Shortdiv].MEMBERS,
{StrToMember( iif(IsError(StrToMember("[Adgang].[" + Mid( USERNAME, Instr (1
, USERNAME, "\" ) + 1 ) + "]")), "[adgang].[All adgang].[UNKNOWN]",
"[Adgang].[" + Mid( USERNAME, Instr (1 , USERNAME, "\" ) + 1 ) + "]" ))},1),
{LINKMEMBER([Shortdiv].CURRENTMEMBER, [Shortdiv])}))))