time machine over afp: authentication problems

I am using time machine to backup to a network drive. I am having two machine and i am able to backup from one machine to the network drive. But on the other machine when i mount the drive, i select it in time machine references. It ask me for user and password. When backup start i get an error saying "the network backup volume could not be mounted because there was a problem with the network username or password." I am finding it odd it is working fine with one machine and not working at all with the other machine.

Even i am having the same problem but i get it solved. I can freshly restored system from a backup. I tried the following and it is working fine for me:
*OFF time machine backup
*Go to start->application->utilities->Keychain Access.app
*Select SYSTEM keychain
*Delete all entries
*ON time machine again
*Re-enter account information
Try doing this hope this will help you.

Exactly the same problem is there in my new iMac and i am getting the same error message after updating iTunes. I tried erasing the keychain several time for time machine but it did not work. Today i heard that they elevated the issue to apple engineers. There is no solution erasing my hard drive and reinstall everything. I did google search but i did not get any solution. Please provide some info to avoid the reformat of my hard drive.

Try this one
1)Make aside your system keychain. CODE:sudo mv /Library/Keychains/System.keychain /Library/Keychains/System.keychain.moved
2)Create new keychain. CODE:sudo systemkeychain -C
3)open system reference-> time machine
4)Click select disk if time machine shows a backup disk configured.
5)click [select backup disk]
6)Choose your time capsule and configure with correct password.
I know you have try some of this step but try these specific steps in this order.

I tried the step in the order listed by you. It seem that Time capsule was going to initiate the setup but in the meanwhile i got keychain error. "Keychain error -25299 occurred while creating a System Keychain entry for the username “xxxxxx” and URL “afp://xxxxxxx@TimeCapsule.local/TimeCapsule”. I perform all the step in the same way but i think it is not working for me. Give me some other suggestion if you have.

Even I tried all the above step. The time machine again ask me for the user/password, I enter the proper user and password and time machine accepted it. I I get a message that the backup will start within 150 sec. After 150 sec it display preparing for backup the it display me the following error message “"Time Machine Error. The network backup volume could not be mounted because there was a problem with the network username or password. [...]"”.

Even I tried all the above step. The time machine again ask me for the user/password, I enter the proper user and password and time machine accepted it. I I get a message that the backup will start within 150 sec. After 150 sec it display preparing for backup the it display me the following error message “"Time Machine Error. The network backup volume could not be mounted because there was a problem with the network username or password.

Even I tried all the above step. The time machine again ask me for the user/password, I enter the proper user and password and time machine accepted it. I I get a message that the backup will start within 150 sec. After 150 sec it display preparing for backup the it display me the following error message “"Time Machine Error. The network backup volume could not be mounted because there was a problem with the network username or password. [...]"”.

When I try loading time machine I got the error message that the network volume could not be mounted due to the problem with the network username and password . This is what fixed my issue.
1)Toggle time machine to OFF
2)Click change disk and in the next window select NONE.
3)Open keychain utility
4)See under System and delete all time capsule entries.
5)see under login and delete all time capsule.
6) On the time machine and select time capsule as backup disk
After performing this, from then on everything worked fine.

On the basis of your information I turned on guest read/write on the server (Airport Utility/Manual set-up/Disk/Sharing/...) When I choose time machine to connect as guest it is getting connected without any error message. And I was also able to back up with no error message. Well even agree that it is not the acceptable solution. Good work by you hope it will help to the people having this problem.

After resetting my Time Capsule, from one Mac I can back up though Time Machine, but from a second Mac the program asked me for username (which I don't use) and password (which I entered.) Backup started, but then I get an error message saying there is a problem with the network username or password. The Keychain in Applications showed the password I entered was correct. SOLUTION: The Keychain in Systems had an old password; I changed it to the new one. Backup then ran successfully.