Useful UPnP Troubleshooter
Universal Plug & Play aka UPnP is used by a lot of networking devices and software to communicate with each other for automatic setup/installation.
Many software programs and games that need inward-bound internet connectivity can automatically configure your UPnP broadband router for their use. Examples of these programs are Instant Messengers such as MSN Chat, and Bit Torrent clients like uTorrent and Azureus.
If your programs are having trouble with UPnP, you can use the following links to troubleshoot, including a handy small program that will detect what steps you need to take to get UPnP going.