Can’t start your browser? Try checking if any torrent apps are running. Close them and retry.

This was a surprisingly common issue back in the day. Torrent clients like uTorrent or Vuze would open hundreds of network connections, and on machines with limited resources this could prevent other applications — including browsers — from establishing new connections.

If closing the torrent client fixes it, you can also try limiting the number of global connections in your torrent client’s settings. Most clients let you cap this under their bandwidth or connection preferences. Reducing it to something reasonable (like 200) usually prevents the problem from happening again while still keeping your downloads running.

Related: troubleshooting.

This mostly affected Windows XP and Vista, where the half-open connection limit was quite low by default.