One of my computers uses Debian GNU/Linux 5.0 Lenny. When I went to boot up this morning, this is what I got:
Decompressing Linux ... Parsing ELF ... done.
Booting the kernel.
[ 0.248015] PCI: Not using MMCONFIG
Loading, please wait ...
udevd [381]: error getting socket: Invalid argument
error initializing netlink socket

udevd [381]: error initializing netlink socket

error sending message: Connection refused

udevadm [382]: error sending message: Connection refused

After 5 minutes of the above data on the screen, this is what came up:

Gave up waiting for root device. Common Problems:

- Boot args (cat/proc/cmdline)
- Check rootdelay=(did the system wait long enough?)
- Check root= (did the system wait tor the right device?)
- Mi8ssibng modules (cat/proc/modules;Is/dev)

ALERT! /dev/sdal does not exist. Dropping to a shell!

BusyBox vl.14.2 (Debian 1:1.14.2-2) built-in shell (ash)
Enter: help for a list of built-in commands.

/bin/sh: can't access tty; job control turned off
(initramfs)

Anybody know what is going on, and what I can do to fix it?

So it was working before? Any recent updates?

I would try booting up in single user mode and see if you can make any sense of the error messages and/or doing a disk check.

If that fails, boot up with a Live CD and check the hard drive that Linux is on.

Thank you for the response pentode. Yes, it was working fine the day before and there was no trouble booting up then. I have been doing updates/upgrades pretty much every day - apt-get update and then apt-get upgrade after the update. I will try a few things and see if I can get something happening. Again, thank you for the tips. I will re-post something here if there are any changes.

Yes, I tried booting up in single user mode and it went to a login prompt. I then typed startx at that prompt, and got this:

Failed to start the X server (your graphical interface). It is likely that it is not
set up correctly. Would you like to view the X server output to diagnose the problem?

< Yes > < No >