Admin account privileges issue in 11.10

One of the two administrator accounts in my system became inactive, i.e. even if the password is entered, there is no response. The screen stays the same, with password window cleared of the stars representing the password.

I'll call one of them "Admin User A" and the other "Admin User B" for clearly explaining the issue. In addition to the two administrator accounts, there are two standard accounts as well.

The problem was encountered by "Admin User A". Perhaps, a possible cause would be any of the following actions performed prior to noticing the hitch:

1. Using the command "sudo apt-get install gnome-session-fallback", installed Gnome Classic desktop (this was for using the app Cryptkeeper which did not work in Unity desktop). The problem, however, did not occur immediately after installing this additional desktop option.

2. Tweaked the security tools rkhunter, chkrootkit, encfs and tiger auditing tool just to get an understanding of their use. However, no crash or other warnings were experienced during these sessions. Most of the actions were either cancelled or aborted, although there is possibility of ignoring an occasional prompt.

3. Use BleachBit regularly to get more disk space.

As a remedy, got the Admin User B to change the log-in password of Admin User A (not sure whether this is an illegal action). This did not answer. Thereafter, got Admin User B to enable Admin User A to log in without a password. Following this, password entry box of Admin User is showing the words "Log In" but hitting the Enter key does not allow log in. Instead, after a brief black screen, password entry box is shown again.

Even after having got Admin User B to remove some of the programs (security tools stated above) which can be suspected to be causing the problem, no change was seen.

After these steps, Admin User B has become unable to change User Account Settings, including that of Admin User B himself (the padlock sign on the top right doesn't respond when trying to make changes inside the User Account Settings dialog box).

The two standard users and Admin User B can still work using the passwords assigned to them. Admin User A cannot log in to the system (Please note it is the Admin User A who did the initial installation) . Standard users can log in and log out of their accounts but cannot shut down or reboot the system. Admin User B can restart and shut down via the terminal but the system does not get shut down. The monitor displays a string of messages about some processes and the CPU seems to be running.

As a temporary remedy, reduced auto suspend time. But the system does not seem to suspend after the set time of ten minutes. So, have to disconnect power manually. Power button doesn't answer too.

I believe I have provided sufficient details here, and maybe this is a serious error. Please advise so I can save a lot of time and some important files belonging to all users.

Thanks in advance.