This is not a bug, it's a feature. You can turn off the browse feature. If you want to know why I'd suggest searching the internet; there are good reasons for it. Blocking people who have the browse feature turned of would necessitate a search for every connection, clogging the network. Also, due to the way the network works, this would probably result in the network being effectively split in two, between those with the browse feature turned off and those with it turned on. Clearly, this is not a good thing, especially for those with the browse feature turned on, since they appear to be in the minority.