I have also been facing this problem for a long time. It began with 12.04LTS as I remember. Previously the system was stable as a rock running 10.04 LTS.
Tried to re-install the OS from scratch, but still facing the problem. Changed Video card, main board. Swapping RAM tried different graphics drivers, different available kernels but there is still random freezing. Could not effort to change the $1000 CPU... To me it happens most often when kicking on a link in Thunderbird to be opened in Firefox. Complete freeze, but the mice some times still moves around. No response from keyboard at all (numloc and capsloc LEDs does not change). Some times the system freeze when running in idle, and I discover this at logon screen. Normal uptime is about two three days between forced HW reboots. The strange about this bug is, that my kids runs a PC Intel Core i7-3770 3,4GHz Asrock/Gigabyte B75-Chipset mATX without facing any problem at all. I'm also user on the PC, running Gnome classic and compiz. I never log out, just switch user. It only reboots when applying new packages that requires a reboot, els its always running stable. Current configuration facing this problem: uptime 12:57:54 up 1 day, 2:22 Gnome Classic + Compiz Linux-x86_64 Intel(R) Core(TM) i7-3960X CPU @ 3.30GHz Kernel 3.8.0-34-generic NVIDIA GTX760 Driver Version: 319.32 /dev/sda Samsung SSD 840 16 GB Main Memory MB Rampage IV Extreme -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/993187 Title: ubuntu 12.04 completely freezes frequently. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/993187/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
