There are many error messages which can be thrown by apache when you try to access your repository. Most of these errors do not have anything to do with TortoiseSVN, but hint at some server misconfiguration. It is also possible that you have simply entered wrong repository URL.
To solve the configuration problems, the FAQ isn't quite the right place, because we need to know a lot more about your server setup. Please come to our mailing list at dev@tortoisesvn.tigris.org and ask your question there. Also, the Subversion mailing list users@subversion.tigris.org might be an even better idea for server configurations.
These error messages hint at configuraton problems:
- '401 Authorization Required'
- '500 Internal Server Error'