Cleaning still happening after being disabled.

Hi, 

We have moved in the direction of creating a build project for each major version of our product.  Each project is really a copy of a master with only a few small changes such as the repository branch its build from and where the artifacts are.  We keep these previous builds so that the artifacts are easily available  support anytime they need them.   

Under Administration | Server Administration | Clean-up Settings I've disabled "Periodical clean-up".   I've also checked in each project under version control that each project does not have "Clean Build enabled.  But with these settings we still find that sometimes that all artifacts are removed from the build directory.  Have I missed something  Could there be another setting that I should change?   

Thanks in advance for any help.

Alex