error code sql server

Good morning
MOM server 2005 prompt this message during the installation
Failed to setup database security.
Error code: -2147217900 (user, group, or role 'SC DW DTS'
already exist in the current database)
what can i do in this casehttp://groups.google.co.uk/group/microsoft.public.mom/browse_thread/thread/9
fc353baf7bde8b8/45c77c865aeb54a8?lnk=st&q=user%2C+group%2C+or+role+'SC+DW+DT
S'+already+exists&rnum=1&hl=en#45c77c865aeb54a8
"Djeff" <e.djeff@.free.fr> wrote in message
news:mn.b33c7d5c80e5082d.46131@.free.fr...
> Good morning
> MOM server 2005 prompt this message during the installation
> Failed to setup database security.
> Error code: -2147217900 (user, group, or role 'SC DW DTS'
> already exist in the current database)
> what can i do in this case
>