Hi there,
Whenever there is a problem with the game, there is a process of elimination to go through, which is what you've been seeing and doing (clearing caches etc), then internet speed/connection, then game connection etc. It really depends on what the problem is as to what you try next, which is what the top post in each official thread is for.
Unfortunately this current issue with flash was an update from Adobe that was released at the same time as our New Release. Although the problem is wide spread, it's not game wide, which means it's more difficult to pin down exactly where the problem is. For example there are many members using the flash in question and are connected to the same servers as those posting issues, but are having no problems with it on either FF or chrome.
If you believe the problem is down to flash player and you have tried the usual fixes, all you can do is wait, either for Adobe to update, or if possible the devs to find a solution that will work for everyone. Just keep an eye on the various threads, someone is bound to post to say when their issue is fixed, and as I've already said, we as moderators, will keep the threads updated as soon as we know.