I've had the same or a similar issue. My computer was constantly renaming itself with a (2) every time it booted, after a system lockup. I tracked the issue down to CD/DVD sharing... when turned off the problem went away.
When CD/DVD sharing was on, I could not change the name back to the original version, it would get rejected and immediately set back to the version with "(2)", displaying the message:
The name of your computer "Name" is already in use on this network. The name has been changed to "Name (2)" automatically.
With CD/DVD sharing turned off, I could name my computer whatever I liked, even back to the original name. Turning DVD/CD sharing back on again would instantly rename my Mac. It's very persistent bug!
Fortunately I found a fix. I was able to get rid of the problem by toggling Bonjour, as described here:
http://tech.karbassi.com/2007/11/06/leopard-turn-off-bonjour-mdnsresponder/
To turn Bonjour off:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
To turn it back on:
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
Toggling Bonjour (mDNSResponder) forced a reset of something on my system somewhere, and now I no longer see the issue on reboot, even with CD/DVD sharing turned on. I can turn sharing on and off at will, and my computer is never renamed. Success!
I don't think this problem has to do with CD/DVD sharing specifically... I think it's a bug in Bonjour. I've seen threads where people have complained about this issue because of printer sharing, or remote management! My guess is that a crash can cause a mDNSResponder config corruption, tricking Bonjour to share devices or services using the same name as your computer, forcing the name conflict.
In any case, I hope this fix works for you too. I know I'm a lot happier now that there isn't a lingering issue on my box!
