Getting "Unable to open http:\\<Website here> The internet site reports that the item...."

The full error is: "Unable to open http:\\<Website here> The internet site reports that the item you requested could not be found. (HTTP/1.0 404)"

I get this in a certain file and any file into which I add a sheet from the first file into. When a file is added to the a clean sheet it will literally take 30-45 seconds to open, and give me the above error 4 or so times whenever I'm opening the file. This is truly frustrating, and the workbook that has this problem is massive, so I can't really rebuild it. The places that it is trying to bring up doesn't even exist anymore.

Whenever I look at links (ALT + A + K) there will be none, and there are no connections. It appears that there are zero links whatsoever, yet I still get this message.

I've googled this error and I haven't found anything helpful. I would post the workbook but the link contains a link to my company's internal website, so I don't think I can do that.

Does anyone have any ideas? I'm desperate.