Trading Post
It’s not an ongoing issue — it affects only certain people and your best bet for resolving it is to contact support: https://en.support.guildwars2.com/app/ask.
The trading post runs as a web application and can be affected by many of the same issues that affect them. There are some common solutions posted in the tech section of the forums, including ensuring that your anti-malware software isn’t interfering with it and that your GW2 folder has admin rights (there are stickies about both those issues).
There are some less common issues, too. Near as I can tell, anyone asking support for help is able to resolve these, ending up with the same 99.99% up time for the TP that most of us enjoy.
Good luck.
John Smith: “you should kill monsters, because killing monsters is awesome.”