Hi Joeb, the key reason you cant disable browsing of your files is for the simple reason the list is not being delivered from you but the primary your connected to, primaries act as file indexers and index your file list when you join the WinMX network, this is the list thats passed around when a browse request is made.
If you are a primary and want to block browsing of your own and (by extention) the secondaries your connected to this is technically possible but not overly trivial, however as Wonderer makes clear we are all pro file sharing here and thus anything that will likley impact on others sharing their content is not good news in our book,and there lies the problem with giving you the full details you may wish to have.