I know what the problem is. I had this exact same issue. You were using one skin, then you deleted it. If you can remember what the name of your old skin was, just rename one of the others to that one (I was using Adv.Evo, but deleted it then renamed Adv.EvoR and everything was breezy). Nothing has frozen or anything, what happens when you press start is that it brings up the start menu, but there are no skin files for it so it's basically invisible. You could also adjust your .INI file to point to a different skin if you don't remember the name of your old one.
As for the download play lag, did you enable the Download Play patch from the start menu? If not, go to "Patches" and enable "Download Play." Of course, you can't do that until after you fix the issue with your skin, but that should remedy your issue. Also, use AKAIO 1.3b2. It's epic.