I recently did a 'dist-upgrade' on my Debian testing machine and now the system stalls at boot. It stops at:

ACPI PCI Interrupt link APCH enabled at IRQ 20

I really don't know how to even begin troubleshooting this since I can't even get into single-user mode.

Try giving it some boot parameters. Like acpi=off or acpi=noirq. Just to get past that line. All parameters are listed here:
http://www.mjmwired.net/kernel/Docum...parameters.txt

You should still have an old kernel or two around. Do they work?

Unfortunately, no. I wish I did. According to GRUB and the /boot/ folder, I'm now using 2.6.26-1-686.

Right now, I'm not even sure if the kernel was upgraded. I went through the list of packages being upgraded and didn't see any upgrades for 'linux-image'. But, then I thought I saw 'linux-image' pop-up during the upgrade process. I think my memory is playing tricks on me.

If the Kernel was upgraded, I should have dual entries in GRUB but I don't.

This is was the first thing I tried. Actually, I tried noacpi. This causes problems loading the SATA drive that has the root partition. It seems to cause the boot process to loop between loading either of my SATA drives and running into a problem with both. I don't remember any of the messages as it doesn't stall like the normal boot, just loops. I do remember something about IRQ 11.

Is the boot process saved to a file somewhere? If it is, then I can access it from Windows. At least then I'll have some key words to help me investigate what's happening when I trigger noacpi.