I'm running an up-to-date Debian Squeeze 64-bit on a laptop. It's usually been stable, as I might expect from Debian Stable. From time to time, though, it freezes at seemingly random times. I notice it mostly when I'm typing and the keyboard stops responding, but I'm not sure it always freezes while typing. I can't do anything at that point, not even select a virtual console.
I can't find an Alt-SysReq key on the laptop keyboard to kill it semi-gracefully, so I kill it with the power button.
When I reboot, it usually boots partway and then freezes again. It's almost always just after it's said it's starting gdm3, checking battery status, or starting ACPI.
Getting past that point is challenging. I've tried disconnecting the power and taking out the battery, but that rarely helps. What usually helps is to boot into Windows (W7, if it matters) and then shut down and boot into Debian. Sometimes it seems to help to pull the battery for a bit, too. Sometimes neither seem to help, and so I keep trying combinations until it reboots.
Does that sound at all familiar? If so, is there a solution (either to keep it from freezing or to recover more rapidly after freezing)? What data (log file, I presume) do you need to help me find and fix the prroblem?