Comment 39 for bug 585765

Just so we don't get too many unrelated freezes being tracked in this thread... the symptoms characterized by florianr were:
- issue was NOT present prior to 10.04
- intermittent system-wide freezes
- frozen image on screen, showing the desktop image without any change and not taking mouse/keyboard actions
- sometimes MagicSysRQ (R-E-I-S-U-B) works, sometimes not.
- system log is still active for some time after the freeze appears to happen
- system logs do not contain any obvious/consistent message that identify the cause of the freeze
- issue is STILL present testing with upstream kernels (except that you may be able to continue moving the mouse or a period of time)
- not a memory issue
- system stays connected via wireless (if using wireless)
- issue appears on very different hardware (intel CPU and. AMD,; intel video and nVidia),
- not related to a specific desktop (gnome and kde) or a specific application (e.g. virtualbox, firefox, etc.)

From my own observations:
- a freeze can be provoked by running processes with high CPU (and possibly disk I/O) such as with handbrake
- I've been able to prompt freezes with no desktop or X server running.... although I don't know if florianr can confirm this on his system. As such, I doubt the problem can be compiz or xorg related (although, note that it may be processor load related, as as such something like compositing could make a system more likely to freeze)
- I can eliminate freezes by booting with kernel parameters "noapic nolapic acpi=off"

florianr, so we can see whether we're still dealing with the same bug or not, could you please verify:
- your system still responds to pings when "frozen" (and you can't ssh in)
- your system doesn't freeze if you boot with kernel parameters "noapic nolapic acpi=off"

Others, if your symptoms are different from those above, you may want to start a new bug report.