On 2 partitions of my HD I have installed Debian 7.7 and Debian 7.8 (upgraded from 7.7). The first OS has "suspend" to ram or disk working, the latter not anymore.
I made some tests, changing home and etc directories, without success. It seems that after restore, the HD is working, but the OS not (it's freezed?). The screen is black and the keyboard doesn't respond. CTRL ALT F1, CapsLock, NumLock don't work.
s2ram and s2disk don't work too.
I did think that it was related to some file in /etc/X11 directory or in /home, that's why I copied those from the working OS to the other.
Can someone tell me what file suspend depends on? I could copy the right one from Debian 7.7 to 7.8. I cannot believe that a so small problem forces a user to reinstall Debian. What the difference from Windows?
Thanks to all who will spend some time to resolve this very common issue.
EDIT: I have KDE, GNOME, LXDE. The problem persists if I change Desktop Environment.
EDIT After upgrading the kernel to 3.2.65-1+deb7u1 suspend works but not hibernate. I installed uswsusp package and now hibernate works.
Thanks to all helping me to solve this annoying bug.