caution
I would be wary of deleting any file that the author recommends. I do have smss.exe in my windows folder, but it is older than when I downloaded the boombox program. Rather than just deleting it, it would be wiser to rename it to smss.exe.old and see if it screws anything up. That way you can name it back if it messes up one of your programs or windows.
For the record, just uninstalling boombox and deleting the sysconfig folder worked for me, and the popups haven't come back.
-Steve G.