Sounds like you have a server configuration issue–specifically a problem with loopback.
Sometime servers have trouble making HTTP requests to themselves via a FQDN. This could be caused by a lot of different things, but your best (first) bet is to have your sysadmin ensure that all your domains exist in the server’s host file, and refer to whatever local IP each virtualhost is listening on. Like:
127.0.0.1 bullfrogs.com
127.0.0.1 tadpoles.com
This is the most likely thing. But if it doesn’t fix things, have you sysadmin explore any other possible complications with loopback and your web server configuration (i.e., can the server make requests to its own sites). This is something the sysadmin should be able to diagnose from the server’s CLI using some quick CURL requests.