I jailbroke my iPhone and when I pull up Cydia it minimizes?

About a week ago I jail broke my iPhone and I've been having alot of fun with it and everything. But starting last night whenever I tried opening cydia it would just minimize to the upper left corner about the third of the screen is the little window and the rest is black. Can someone help me?

Try restarting the phone
If that doesn't work, jailbreak again