My deck was a bit big and my browser found it to take a bit too long and asked me whether I'd like to shut down the script that was loading my deck for taking so long. I don't remember being able to select no, but the next thing that happened was my deckbuilding screen spazzing out like shown below:
...
It does show the card counts correctly but seems to have replaced all images with the Quantum Pillar image and just flicker. Anyone else experienced something similar?
EDIT: neither import/export nor the menu button were responding, after refreshing everything was fine.