Question about Some of the Mavericks Voices

Hello everyone. I've been experiencing a slight problem with some of the built-in voices in the latest version of Mavericks. Some of them seem to have gotten distorted, and in some cases they stop working as I'm navigating with my arrow keys or typing. The ones that have done this are Fred, Bruce, and I think all the default female ones. I am currently using Tessa, and she seems to be working fine. Alex is working pretty well too. I don't currently have anything downloaded on here except for Google Chrome. Just wondering if this is something I need to be concerned about or if it will improve overtime.