12.04suspend
I have been facing this issue from the last week after some update. Whenever my laptop wakes up from suspend state it just shows me a blank screen. Regardless of whatever I do(move my mouse, press keyboard buttons) it just refuses to wake up. I am forced to do a restart and lose all my unsaved files. Has this issue been reported for Ubuntu 12.04?
I am using a Lenovo X200 with Intel Mobile 4 Series Graphics Chipset. Please let me know if any body has found a fix for this.
I've just had the same issue today, on a freshly installed 15.04. My problem was about the animation on the Google Chrome download page, and my graphics card's driver's not being able to handle it. I am using an Nvidia graphics card, so I tried installing proprietary Nvidia driver and problem solved.
I suggest you try installing/updating the driver for your graphics card, to do so you can check Additional Drivers tab of the Software & Updates in System Settings:
Best Answer
I has this issue on my X200. Workaround for me was:
Turn off screen lock in the "Brightness and Lock" settings.
The only problem is that it wakes without a password, which isn't too big of a deal for me.