We are facing the same issue as well...But we have other problems...OLAP Session times out after 25 mins...We are not sure what is causing the timeouts...weather sso is failing or Sqlserver or Datapump is timing out we are Not sure.
We are also in BO 4.1 SP6 level Sql server MSAS database.
Any Help / Ideas is appreciated.
Regards
Partha