Can't connect to server warning, when there is no server

I keep getting this annoying window popping up telling me it can't connect to my old G5, which it calls a server. I connected to it to download some files and now it won't forget it. Anyone know how to stop it doing this? It hasonly just started to happen in the last week or two.

I have told it to forgetall servers in Finder, deleted all cache files, rebooted, run Disk Warrior, everything and it still pops up. I think it has something to do with Mailsync, as that what it mentions in the console message below.

In the console sync/syncservices.log, I get this message,

2012-10-12 15:49:59:556|SyncServer|6523|0x7f950a40bce0|DataManager|Warning| Client com.apple.Mail sync alert tool path /Volumes/Big Mac/System/Library/Frameworks/Message.framework/Versions/B/Resources/MailSync does not exist.

It is getting very annoying when I am concentrating on something and up pops this window!