I can usually edit them, but a problem comes with submitting the edit in quick-edit mode. Usually hitting the advanced view button and then submitting it clears up this problem entirely. I'm not sure why the quick edit (edit in thread without moving away from the page) doesn't work, while the new page loading advance edit page does. It's pretty much a 25%:100% quick:advanced on whether it works or not.
On that note, it's the same with the quick reply versus advance mode reply. I have a supposition that it has to do with the inline jscript used for the quick mode reply/edit posting, it seems when you press submit, it just loads forever, I've not taken the time to examine the traffic difference in what I'm sending out data wise between the two submission modes. I will check it out when I get home, I'm sure the problem lies in there somewhere.
Also Important News forum, you cannot edit posts. They just need to fix that, problem with the admin there.