This has been a long standing problem with Steam and some other games with lots of servers too, basically, your computer sends the request for the list and because the server details are returned by UDP instead of TCP there is no wait for an ACK (accept packet) in between sends so your router gets flooded at the full 100MBPS or whatever it happens to be causing some routers to fall over- otherwise you just don't get a full list, just bits and pieces.
Hope that makes sense
