[ubuntu-za] Update broken - any ideas?

[Zabear]

Hi all,
since 18 jan I have a problem updating. I'm using Ubuntu 12.04 LTS.
After updating on the 18th I got an error message.

the error message is the following: It is impossible to install or 
remove any software.
Run 'sudo apt-get install -f in terminal'

I did
messages came back:
'dpkg was interrupted - manually run 'sudo dpkg --configure -a'

I did
message came back
'error: failed to open '/var/lib/dpkg/status' for writing status database
no space left on device'

but there are gigabites of space

it seems as if it is trying to find a new device called /dev/sr0 , in 
directory /media/DSL-275OU of type iso9660  which has apparently 
124,5MiB but 0 bytes free.

I do not have such a device such as /dev/sr0      !

But now I cannot update and I struggle to open files.

Any advice?

Rusty