MSDB in suspect mode.

Hi,

I have mssql 2005 installed and i see that MSDB database is marked as suspect. I almost tried all the steps which are submitted in the forums.

1) I shut down the server, navigating to the directory 'd:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Binn' and doing the following: start sqlservr.exe -c -T3608
2) renamed the damaged msdb files (msdbdata.mdf and msdblog.ldf in the 'd:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data' directory)
3) Run the instmsdb.sql script in the 'd:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Install' directory

--x---
When I executed third step it returned me below error:
Msg 926, Level 14, State 1, Line 63
Database 'msdb' cannot be opened. It has been marked SUSPECT by recovery. See the SQL Server errorlog for more information.

Please advice me.