linux-image-generic for 686 not 386

The following NEW packages will be installed:
  linux-image-2.6.20-16-generic
The following packages will be upgraded:
  linux-image-generic
1 packages upgraded, 1 newly installed, 0 to remove and 43 not upgraded.
Need to get 23.8MB of archives. After unpacking 71.3MB will be used.
Do you want to continue? [Y/n/?] Y
Writing extended state information... Done
Get:1 http://security.ubuntu.com feisty-security/main linux-image-2.6.20-16-generic 2.6.20-16.29 [23.8MB]
18% [1 linux-image-2.6.20-16-generic 4410339/23.8MB 18%] 19.1kB/s 16m57s
Message from syslogd@jeffrey-desktop at Mon Jul 30 12:17:01 2007 ...
jeffrey-desktop kernel: [ 5862.549562] journal commit I/O error
Err http://security.ubuntu.com feisty-security/main linux-image-2.6.20-16-generic 2.6.20-16.29
  Error writing to output file - write (30 Read-only file system)
Err http://security.ubuntu.com feisty-security/main linux-image-generic 2.6.20.16.28.1
  Could not open file /var/cache/apt/archives/partial/linux-image-generic_2.6.20.16.28.1_i386.deb - open (30 Read-only file system)
touch: cannot touch `/var/lib/update-notifier/dpkg-run-stamp': Read-only file system
E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/l/linux-source-2.6.20/linux-image-2.6.20-16-generic_2.6.20-16.29_i386.deb: Error writing to output file - write (30 Read-only file system)
E: Unable to open /var/log/aptitude to log actions - do_log (30 Read-only file system)
E: Problem executing scripts DPkg::Post-Invoke 'if [ -d /var/lib/update-notifier ]; then touch /var/lib/update-notifier/dpkg-run-stamp; fi'
E: Sub-process returned an error code
A package failed to install. Trying to recover:
dpkg: unable to access dpkg status area: Read-only file system
W: Not using locking for read only lock file /var/lib/dpkg/lock
jeffrey@jeffrey-desktop:~$

What happened? How to recover? Should/Can I sudo rm linux-image-generic?

What command did you use, exactly, to start the installation?

Any chance any of the volumes in your machine are full?

The usual sudo apt-get install linux-image-generic.
The /dev/sda1 partition which is / is 7.8GB so do you think that the volume is full?
Is there any way to repair hard disk errors and bad blocks - what is the command from terminal?

The key message seems to be "journal commit I/O error" in the middle, after which the filesystem immediately became read-only.

A few searches suggest this might be a kernel bug, but it might equally be a problem with the disk. If you run "sudo touch /forcefsck" and then reboot, a disk check will be run on all filesystems. It won't check for hardware-level bad blocks (the "badblocks" command does that), but don't worry about that just yet.

If, when you try again, you're able to upgrade the kernel and the problem goes away, it's likely that it's a kernel bug that has been fixed. If the problem recurs each time before you're able to upgrade the kernel, one option is to temporarily mount the filesystem as ext2 instead of ext3 (ext2 has no journal). If it's the root filesystem (/), the easiest method is to change the entry in /etc/fstab from ext3 to ext2 and reboot. Don't forget to put it back to ext3 when you're finished!

Whatever you try, remember that something in your disks or filesystems isn't happy. Make sure you have a backup of everything in case it all goes horribly wrong.

I don't think it's relevant, but you can check disk space available with the "df" command. And finally, no, there is no 686-specific kernel any more. The generic kernel is able to select the optimisations appropriate to whatever CPU it detects it is running on.

Good luck!