Model Deployment fails - Error code: PerformancePoint_1050200270

A couple of days ago, after installing PPS2007 SP1, I've created simple application called UserTest and tried to deploy model site. It failed with following error:

"The attempt to deploy, UsersTest, to the model or model site failed. (Error code: PerformancePoint_1050200270)
Failed generate and process of Olap object(s): Internal error: The operation terminated unsuccessfully.
Internal error: The operation terminated unsuccessfully.
OLE DB error: OLE DB or ODBC error: Login failed for user 'NT AUTHORITY\NETWORK SERVICE'.; 28000; Cannot open database "UsersTest_App_Db" requested by the login. The login failed.; 42000; Invalid connection string attribute; 01S00.
Errors in the high-level relational engine. A connection could not be made to the data source with the DataSourceID of 'feec5192-c4eb-41c4-8b38-8a9ee2cbedc0', Name of 'AppDB'.
Errors in the OLAP storage engine: An error occurred while the dimension, with the ID of 'Time', Name of 'Time' was being processed.
Errors in the OLAP storage engine: An error occurred while the 'MemberDescription' attribute of the 'Time' dimension from the 'UsersTest_UsersTest' database was being processed."

Hmm, strange..Yesterday everything worked smooth (argh, how many times I'm saying this). So I've made a little investigation and here is the result: Network Service must be granted enough privilegies under SQL Server (both relational and analytical engine!). For example, situation with this account in our database was that it was defined as public role. So I've granted administrator privilegies and everything worked again. Please note, that you have to grant enough privilegies both under relational engine and SSAS!