Thread:Project:Support desk/Receive 404 error when adding more than 3 links to URLs on a page./reply (3)

It's a problem with your webhost (for Kalki kalki. 99.13.234.88 didn't provide a url, so I can't test, but I would assume the same thing applies to him/her). The error is not a 404 error (despite what the web page says), but actually a 403 (forbidden) error. This is probably some sort of poorly thought out anti-spam protection done by your host. You should complain to your web host.

If you're running your own webhost, apache modules mod_security and mod_security2 are known to cause issues somewhat similar to this.