For the past few weeks, when opening the lid my laptop often fails to recover from suspension leaving me with a blank screen. Further, when this bug occurs, the laptop fans continue to run while the lid is closed, causing my laptop to quickly overheat in my bag. I have read various different questions on here that had similar symptoms but none of the solutions worked in my case. Disabling suspension on gnome seemed to reduce the frequency of this issue, but it still occurs with some frequency. It only seems to occur if I do not lock the computer before closing the lid or I am in a different desktop manager (such as dwm). I currently have the ATI graphics drivers enabled (not sure on the specific driver, but it is whatever driver that Jockey installed).
When the fans continue to run, that would indicate the laptop has not in fact suspended correctly - not that it's not coming out of suspension correctly.
I would suggest testing suspend by running the "suspend" command in a terminal, while the laptop is open. This will let you see error messages more readily if any are displayed, though the fact that it's the display driver probably causing the issue will probably hamper that somewhat.
If you see the same behavior, I would suggest removing the proprietary ATI drivers and trying again. (http://askubuntu.com/questions/68306/how-do-i-remove-the-propretary-ati-drivers might help for that) If that makes suspend work ,the proprietary drivers are the cause of your suspend problem. If not, then it is some other driver in use on your system.
Any kernel module loaded (such as the proprietary ATI driver) can interfere with suspend, because each module needs to be able to move its hardware to a low power state correctly, and then restore the hardware afterward. A launchpad bug here https://bugs.launchpad.net/ubuntu/+source/fglrx-installer/+bug/677917 shows you are not the only one with this issue due to the fglrx module.
The report there suggested adding a file "/etc/pm/config.d/unload_modules" containing
however he also mentions that this did not work consistently.