"bs.serving-sys.com/serving/adServer.bs?cn" etc on my browser

Hello JeriB2,

Thanks for reaching out to us in Apple Support Communities about receiving a error when attempting to load a website, we're happy to help by looking into this more! 

The following support article provides some troubleshooting steps to try for this behavior:

If Safari on Mac doesn't open a webpage or isn’t working as expected

We also noted that you are running a Mac with an older version of Mac OS X installed, that may also be the issue. The website you're trying to load may require a computer with a more up to date operating system. If your Mac is capable of being updated, this article can help with that process:

Update macOS on Mac

If you Mac is not able to be updated, it can limit access to certain websites.

Hope this helps.

Best Regards.

Usually when the website is going to some place unexpected, you have a redirect extension in Safari menu -> Preferences -> Extensions that needs to be removed.

Quit and restart Safari holding the shift key to force it to restart the homepage and not the last page loaded.

Also, according to your signature, you are using El Capitan, not Leopard, an operating system 6 years older.

https://discussions.apple.com/community/mac_os/os_x_el_capitan