I installed hundreds of times Virtualmin/Webmin on Linux machines. This is a fresh install Debian 7.8/Virtualmin.
1) I login into Webmin account then I visit some sections. Over a while I get page not found for a section then the whole webmin content is not found.
2) I refresh the window, I can start again visiting sections, but over a while without activity visiting a section I get page not found.
3) I restarted webmin service. Same behavior. I restarted the whole server, same behavior.
Service webmin is running. I really don't understand what is going on. You can see in attachment the page I get in Chrome.