10.04 upgrade "complete" but sys hangs on restart

[pjstock]

my system proposed an upgrade to 10.04.
I (foolishly?) thought OK, and let it run overnight.

this morning it seemed to complete, restarted itself.

it gets to the UBUNTU logo, shows "Starting Up" and then.... nothing. it just hangs with a blank screen.

when I've faced a crapped out upgrade before on another machine I had to reinstall from an old 9.04 CD and then upgrade again.

when I start that process at the Partitioner it is showing me that "Ununtu 10.04 is installed" and asks if I want to replace it with 9.04

I would like to avoid the downtime of that reinstall and reupgrade process. is there anything I can do at this point to revitalize my 10.04?

(and in general, is this a fairly common problem? crapped out upgrades? in my 2-years of using Ubuntu this is the 2nd time I've faced a failed upgrade.)

Peter

[quixote]

Broken upgrades happen, unfortunately. The faster and better your connection, the less likely it is. E.g. it's best to use ethernet cable instead of wireless when upgrading.

The first thing I'd try is to boot into recovery mode when grub gives you that choice, not into the usual graphical mode. (It sounds like it hangs after grub, is that right?) Have an ethernet cable plugged into your computer. When it gives you a choice of boot modes, select the one near the bottom "root access with networking".

After a whole mass of boot messages go flashing by, you'll be at the root prompt. (Don't make any typos because root can do anything, even wipe out your system.) Run this command:
dpkg --configure -aIt should go to the repositories and fix whatever is broken. If it doesn't, come back with the error message it gives you, and we'll take it from there.