There's 2 very similar threads going on right now side-by-side. I just posted this so I'll post the exact same thing here as well.
Not listed in my "steps" -- this is optional:
AH Skin Viewer It's an older version (but it's the most recent one available) so until they get it up-to-date, it will force you to rebuild your cache every time you start up Aces High after using the skin viewer. I've just been using the game for viewing skin progress, but when you need to fine-tune things quickly, the skin viewer really helps.
It just usually stops working right after every patch.
The other thread can be found
here. It may or may not answer other questions you have.