I just flashed my w580i and it's 10x better than when I originally got it from at&t. I used xs++ v3.1 and used these forums to help me out. Now I want to add more things like flash themes, walkman skins, etc. The tutorials on here say to use FSX to install them but everytime I open up xs++ and connect my phone, the "START FSX" button is not pressable. I can't click on it! The program doesn't freeze up or anything. All the files I want to upload are in place but I can't get it to start. any ideas? is it a program bug or my phone? is there any other way to do it?

hhmm strange i use fsx on my w580 all the time. make sure you have the latest xs++.
alternatively you can try using setool2 lite.