Trying to backup two computers via Time Machine on Time Capsule

Question

Hi, everyone.
I have read about a similar problem that I am having, but the forums were all from 2009, so I don't know if anything has been updated or figured out since then.
I bought a Time Capsule yesterday, and I set-up a network as well as the Time Machine configurations.  My iMac running 10.6.8 did just fine backing up; however, my Macbook running 10.5.8 did not.  
When I try and run a backup with Time Machine, I get this error:
"The network backup volume could not be mounted because there was a problem with the network username or password."
After that error, I get this error:
"Keychain error -25299 occured while creating a System Keychain entry for the username "XXX" and URL "afp://[email protected]//XX".
I have searched different forums for hours, and so far, based on what I have been reading, I have done this:
1. Deleted anything having to do with the TC in the keychain and trying to restart the backup.  This made me have the same errors again.
2.  Reset the PRAM. 
3. Repaired disk permissions.
4.  Repaired keychain permissions.
Finally, I found on a forum that I could set up guest access on the network and backup my Macbook as a guest.  This is what I am doing, now.  However, I saw that starting with OS X 10.6, there was some kind of update for Time Capsule and Time Machine in regards to using Time Capsule for multiple computers.
My question is, since 2009, has there been a fix for this?  I know some people suggested updating firmware, and if this is the fix, what do I need and where do I get it?  Also, would it be possible to purchase OS X 10.6.8 for my Macbook and update it to potentially solve the problem?  Is updating the Operating System hard?  I'm not completely computer illiterate, but I am not great, either.  If I update the Operating System, will all of my files and applications remain on my Macbook?
Thanks in advance for any help you can provide!

Answer 1

Well, there is a way to reinstall without erasing the drive. But it may not fix the problem. You may need to start from scratch. In any event you should make a backup of your system then you do not risk losing anything but some time.
But the real problem I see is that it is the computer that is the problem not the TC which seems to work fine with your iMac.
Since you are using Leopard you can do the following. In my opinion I would not opt to preserve user accounts and network preferences since your problem may well be in your user account.
How to Perform an Archive and Install
An Archive and Install will NOT erase your hard drive, but you must have sufficient free space for a second OS X installation which could be from 3-9 GBs depending upon the version of OS X and selected installation options. The free space requirement is over and above normal free space requirements which should be at least 6-10 GBs. Read all the linked references carefully before proceeding.
1. Be sure to use Disk Utility first to repair the disk before performing the Archive and Install.
Repairing the Hard Drive and Permissions
Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger, Leopard or Snow Leopard.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now restart normally.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Do not proceed with an Archive and Install if DU reports errors it cannot fix. In that case use Disk Warrior and/or TechTool Pro to repair the hard drive. If neither can repair the drive, then you will have to erase the drive and reinstall from scratch.
3. Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When you reach the screen to select a destination drive click once on the destination drive then click on the Option button. Select the Archive and Install option. You have an option to preserve users and network preferences. Only select this option if you are sure you have no corrupted files in your user accounts. Otherwise leave this option unchecked. Click on the OK button and continue with the OS X Installation.
4. Upon completion of the Archive and Install you will have a Previous System Folder in the root directory. You should retain the PSF until you are sure you do not need to manually transfer any items from the PSF to your newly installed system.
5. After moving any items you want to keep from the PSF you should delete it. You can back it up if you prefer, but you must delete it from the hard drive.
6. You can now download a Combo Updater directly from Apple's download site to update your new system to the desired version as well as install any security or other updates. You can also do this using Software Update.