All of a sudden some of my permalinks have changed and do not work

[Ruralinfo.net]

I began receiving emails from people telling me when they clicked on some of my links, they came up with Error 500.  These links changed somehow..

For instance, this is an original link which no longer works:

http://n2.nabble.com/2007-National-Convention-f4933528ef581397.html

After investigation, it seems the link has somehow changed to this, which now works:

http://rural-mail-talk.581397.n2.nabble.com/2007-National-Convention-f4933528.html

I have gone through and corrected a few of these but I am wondering what is going on with it.  

[Peter <Nabble>]

All the addresses change when you set up a domain name. Did you do it recently?

[Ruralinfo.net]

Hi, thanks for the reply.  No I did not change my doman at all.  It was all working fine until I tried to start updating one of my forums for a yearly project I have on my website.  

[Peter <Nabble>]

On this set up, did you use the feature at "Options->Editor->Change Domain Name"?
I'll try to check it up for you.