History:

It once was a free and open AP to acces.
Then changed it to WEP to test the fully automated cracking program, and it worked.
Then I changed it to WPA and I've put in the WPA key correctly.
Then, flashed the phone and put everything back on it, nothing new really.
Network was working..
But after a while it stopped showing up, and it's available on other devices..

What the hell caused this?
Sorry for my bad english >.>