Having some serious screen lock freezes

[Guest nabby21]

As the title suggests, my san francisco keeps getting stuck on the lock screen. Once its unlocked, its fine, works a charm, but that lock screen has currently got me stuck for several hours and counting, which led me to hear. Is there any help/suggestions anyone can offer? Is there diagnosis to find if its hardware/ software etc? Pressing the power button on and off can work after a few goes, but this time it has not..any help?