11.10 version asks for pswd for new apps

What is the complete and exact text of the error message, if any?

Also, please open a Terminal window (Ctrl+Alt+T) and run this command (by copying it to the clipboard, pasting it into the Terminal, and pressing enter):

lsb_release -a; uname -a; groups $USER; gconftool -R /apps/gksu; sudo echo success

You may be prompted for your password. If so, enter your login password, and press enter. Don't worry that you don't see any placeholder characters, like *, and that nothing seems to be happening when you enter your password. Try to type it carefully--if authentication fails, maybe type it again. But this is a diagnostic procedure to determine if authentication of a certain kind is broken on your system, so it might not work. Whether or not it does, please then select all the text in the Terminal (Edit > Select All), copy it to the clipboard (Edit > Copy), and paste it here.

konleo@konleo-MS-7528:~$ lsb_release -a; uname -a; groups $USER; gconftool -R /apps/gksu; sudo echo success
LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch
Distributor ID: Ubuntu
Description: Ubuntu 11.10
Release: 11.10
Codename: oneiric
Linux konleo-MS-7528 3.0.0-12-generic #20-Ubuntu SMP Fri Oct 7 14:50:42 UTC 2011 i686 i686 i386 GNU/Linux
konleo : konleo adm dialout cdrom plugdev lpadmin nopasswdlogin admin sambashare
 disable-grab = false
 force-grab = false
 save-keyring = session
 prompt = false
 sudo-mode = true
 display-no-pass-info = false
 save-to-keyring = false
[sudo] password for konleo:
Sorry, try again.
[sudo] password for konleo:
Sorry, try again.
[sudo] password for konleo:

To clarify things a bit,
I used a pswd to install and uninstall software on the 11.04 version. Now the same pswd does not allow me to do this on 11.10.
The above script is from your guiding.
The message says- Your authentication attempt was unsuccessful

Everything looks to be in order, so it's most likely that the password got changed or corrupted. Try resetting the password: http://www.psychocats.net/ubuntu/resetpassword

using the shift key the system does not go into recovery mode so as to change the pswd.
i also tried to boot from a usb but it does not allow me to install because of the pswd.
is it haunted?
any other suggestion would be helpful.
thanks

First, try https://help.ubuntu.com/community/LostPassword#The_Other_Way. (If you find those directions confusing, then after it says "Your system will boot up to a passwordless root shell," you can start following the instructions at http://www.psychocats.net/ubuntu/resetpassword.)

If that doesn't work, then in your Ubuntu system, open a Terminal window (Applications > Accessories > Terminal) and enter this command exactly (you can copy and paste it)

mount | grep ' on / '

and press enter to run that command. You should see something like:

/dev/sda1 on / type ext4 (rw,errors=remount-ro,commit=0)

The part you're interested is the device name before "on" (in this example, it's /dev/sda1). Remember that, or write it down.

Now boot the computer from an Ubuntu Desktop Install CD (you can burn the .iso image to a CD or DVD, or write it to a USB flash drive and boot from that) and select Try Ubuntu. When the desktop comes up, run the Terminal and, in the Terminal window, run:

sudo mount /dev/sda1 /mnt

If the device name was different from /dev/sda1, put what you saw instead. Then run the commands:

sudo chroot /mnt
passwd USERNAME

Replace USERNAME with your actual username. This will enable you to type in a new password. Enter your new password twice, as it requests. It's OK that no placeholders characters (like *) appear while you're entering your password.

Then run these three commands:

exit
sudo umount /mnt
exit

The last of those commands quits the Terminal window. Reboot the system by clicking the power icon on the upper-right corner of the screen and clicking Restart. Make sure to remove the CD before the system boots up again, so that you can get into your Ubuntu system on the hard disk. Now that you've reset your password, you should be able to authenticate when necessary.

It seems that all I had to do was to open the terminal write
ls /home
passwd username
write the passwd
retype it
and that's all.
Thanks for the help