Hi fellow Concretier's!

I'm having a trouble with my New Custom theme I've created.
I installed my theme and when activating the theme this error occur "Invalid form token. Please reload this form and submit again."

I've done and fixed this error before, I re-installed my theme and it works. But for now when I'm removing the theme, activate other default themes the error still occur.

Please help me about this. Your response can help me alot. ^^

Thanks.