Hi all,

On my folks computer I'm getting the most frustrating experience when I try to go into the network control panel (they're on 10.4.11). They have my old broadband router and when I go to check the control panel under system preferences the message "Your network settings have been changed by another application" appears and the moment you dismiss it, it reappears...and never goes away no matter how many times you click OK. It pops away and then comes back straight away.

It means I can't make any changes in this area at all and I can't seem to stop it. Anyone know the cause and the way to solve it?

Cheers, Phil

Well-known problem. You can probably find the answer via Google, but to save you searching here is my solution.

(This problem does not affect Mac OS X 10.5 or later.)

Somewhere around mid 2008, Apple released a security update for 10.4.11 which changed the mechanism it used to store PPP account passwords. Prior to that point they were in a lightly encrypted file which was easy to crack if you knew how. After that, they were stored in the keychain, which is much more secure.

It appears they fouled up the process as far as System Preferences was concerned, and it was never fixed in subsequent security updates.

You see this repeating message about your network settings being changed by another application if you have any network interfaces with PPP passwords that have been entered (for any "Location", not just the active one). System Preferences is unable to read the password(s) from the keychain because it has not been authorised to do so, and it displays a misleading error message.

The best way to fix this depends on whether you actually need to continue using the PPP passwords.

The first step is getting into the Network preferences without bumping into the error message each time. There are two ways to do that:

(a) If you are currently stuck on the repeating message, force quit System Preferences. Then launch System Preferences again, select the Security settings, and enable the option "Require a password to unlock each System Preferences pane". This option bypasses the problem, because it provides the necessary authorisation to access the keychain.

At this point you can either leave the security setting enabled permanently, or proceed with the later instructions to fix the problem, then the security option can be turned off again.

(b) If you time it right, you can get past the repeating error message. The trick is to use the Return key to activate the OK button, then just after the error message has slid up, click on one of the menus at the top of the network preferences (Location or Show). You may need to try several times to get the timing right.

Once you can get into the network preferences or bypass the error message, the trick to fixing the problem permanently is to go through all network interfaces which have a PPP password entered (possibly for every Location), and re-enter that password. This will typically be all "Internal Modem" or "External Modem" entries.

During this process, the system will ask for permission to allow System Preferences to access the keychain. Once you have allowed it, the problem is fixed (at least for that password).

If you don't need to use the PPP connections any more, you can simply delete the password rather than retyping it.

Thanks. I found the first one by Googling but I had no luck with it. I'll give the second one a go and see how I get on.

Phil