Since this was the original thread that reported this bug, I wanted to confirm that this is still in fact an issue. The main issue of "crashing" has been resolved -- however it now disconnects you for even being in the Party Quest lobby. My character was trapped in the map area because if you even moved a certain distance, you would disconnect. You try to use the soaring skill, you would disconnect. I tried every single channel as an alternative; to no avail. Luckily I was able to make it out using the portal on the left after several attempts.
This has been an issue, albeit the "issue" itself seems to be fluid and ever-changing, for what seems like several months now. I remember quitting over a year ago and distinctly remember that Dragon Rider PQ was a crash-area and to avoid at all costs. To date, this is still an issue.
My recommendation: Remove the Dragon Rider monster cards from the Leafre set indefinitely, or until there is complete verification of a fix and that Dragon Rider PQ is stable.