Thank you, jfaughnan, for posting. This solved my problem, after upgrading from OSX 10.6 (Snow Lepoard) to OSX 10.9 (Mavericks) on my Late 2008 MacBook Pro! I actually use the speech synthesis a lot to help my eyes with reading long articles.
When I looked at the Login Items under my user preferences, I noticed two instances of speechsynthesisserver.app in the login items. I believe that this is because one was from the Time Machine backup. I removed the one that I was able to remove with the lock icon in the "locked" position.
After, I logged out, and logged back into my account and the error message no longer appeared.