Admin password not accepted anymore - but it's correct

Hi,

i have a strange problem in Lion 10.7.5:

My admin password is not accepted anymore in Lion. Whenever i'm asked to enter the Admin password, the window closes (therefore: no "wrong password" message or something else) but the process isn't continuing (for example an installation). There is no change or progression.

The password is definitely correct, i was also able to change it or use it in the terminal (where it is accepted). But i'm still not able to use it within Lion.
Tried also to boot in single-user mode and change the password there via "passwd username" but i'm getting a "The daemon encountered an error processing request" error message.

Read somewhere else, that i should repair permissions and/or try keychain first aid. Tried both but the problem still exists.

Does anyone have another idea? I really don't want to restore my system... Actually, how can i do this without an installer disc? Purchased my imac with lion pre-installed - i guess i would have to reinstall all my applications?

Thanks for your help!
Taner

 

Thanks for your answer.

Things got worse with resetting the admin password, i couldn't login to my system since the autologin feature was turned off after that somehow. Well, in the end i managed to enable autologin via the terminal again, but i had enough of this mess -> clean install -> everything is fine now.