Cannot delete a file - could it be ext3 related?

["Donatas G." <dgvirtual@akl.lt>]

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I have a problem with system upgrade (Kubuntu Edgy to Feisty) which is caused 
by the systems inability to remove a corrupted file. I suspect this could be 
filesystem related, so I am writing to this list. 

Since I am not subscribed, COULD YOU SEND ME RESPONCES DIRECTLY?

I ran fsck /dev/hda5 (my partition) to no avail - the filesystem used to 
contain errors, but they are all corrected before this upgrade.

Here is the story:

## trying to remove the showstopper package:
dg@bala:/var/lib/dpkg/info$ sudo apt-get remove libidn11-dev
...
dpkg: error processing libidn11-dev (--remove):
 Package is in a very bad inconsistent state - you should
 reinstall it before attempting a removal.
terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string::_S_construct NULL not valid
Aborted
dg@bala:/var/lib/dpkg/info$ Errors were encountered while processing:
 libidn11-dev

## trying to update the showstopper package:
dg@bala:/var/lib/dpkg/info$ sudo apt-get install libidn11-dev
........
Preparing to replace libidn11-dev 0.6.3-1 
(using .../libidn11-dev_0.6.5-1build1_i386.deb) ...
Unpacking replacement libidn11-dev ...
dpkg: error 
processing /cdrom//pool/main/libi/libidn/libidn11-dev_0.6.5-1build1_i386.deb 
(--unpack):
 unable to install (supposed) new info file `/var/lib/dpkg/tmp.ci/postinst': 
Operation not permitted
Errors were encountered while processing:
 /cdrom//pool/main/libi/libidn/libidn11-dev_0.6.5-1build1_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

## trying to remove the showstopper package:
dg@bala:/var/lib/dpkg/info$ ls -lo libidn11-dev.postinst
-rwxr-xr-x 1 root 36864 2007-04-25 09:09 libidn11-dev.postinst
## the date is new because 
## dg@bala:/var/lib/dpkg/info$ sudo touch libidn11-dev.postinst
command was the only one that did work on this file :)

## trying to chmod the file
dg@bala:/var/lib/dpkg/info$ sudo chmod 777 ./libidn11-dev.postinst
chmod: keičiamos `./libidn11-dev.postinst' teisės: Operation not permitted

## Trying to force remove the file...
dg@bala:/var/lib/dpkg/info$ sudo rm -f libidn11-dev.postinst
rm: cannot remove `libidn11-dev.postinst': Operation not permitted

I am forwarding the contents of the file: kate editor describes it as a 
binary, it contains a short bash script with all kinds of junk (including my 
mail addresses and headers) at the end...

Google did not help me. Could someone explain what is happening?

-- 
Donatas Glodenis
http://dg.lapas.info

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