CoreBOSBB

Is possible lock any new changes when opportunity sales stage is closed win, or close lost ?

I need restrict new modification only a admin user.

Yes, you should be able to do this easily. There are at least four ways:

1.- Freeze procedure
Which more or less goes like this:

make the module private, so all users can see only their records
create one user in his own hierarchy/role
add an exception so that all users can share their opportunities except this one user
add an exception so that special user shares his opportunities in read only mode
add a workflow that assigns all closed opportunities to this special user

rslemer