I have a file called /Users/PortDetect.log on my MacBook Pro, with contents like
Wed Nov 25 18:22:42 2009 -- PortDetect started... Wed Nov 25 18:23:19 2009 -- PortDetect started...
Who is making this log file? It is in a rather weird location, so I am assuming that it is not something that is part of the OS.
A quick search on Bing or Google of that filename returned this page as the first result. Have you used a mobile Internet card on this computer? The brand that I’m seeing is T-Mobile Web ‘n’ Walk.
To uninstall, follow instructions on T-Mobile’s website.
I removed the portdetect.log file by removing two folders in the /Library/StartUpItems Folder. HWNetMgr and HWPortDetect folders were sent to the trash, then I restarted my Mac. Deleting the log file itself will not work because HWPortDetect will replace it automatically.