Guild Wars 2

For some reason, when I use the Black Lion Trading Company to sell stuff, it randomly chooses when to make my whole screen go black, I can simply do everything else, but I have no video or UI on my screen.

This is what happens when I use Black Lion Trading Company sometimes

Same thing is happening to me. I am using Win 8 and when I minimize the game I can see the bltc in the small window before maximizing the screen back.

I had this problem in the past when I had automatic windows updates enabled. They would install in the background and the BLTC would only operate properly after I rebooted so the updates could be applied. Hope this helps you out.

Try the method in this thread, solved the issue for me: https://forum-en.gw2archive.eu/forum/support/bugs/Trading-post-broken-5. I got a black screen for a few seconds, but it disappeared and I was able to use gem store again.