This is the situation, trying to access 192.168.1.1 with Bitdefender installed will result in a fail - well, there is a workaround.
The problem with Bitdefender is that when you try to access 192.168.1.1 the system will not forward you to 192.168.1.1/login.sh - so what is the solution? Access the address directly.
Go to 192.168.1.1/login.sh and you will get the normal login page, after filling in the password you will get a Page not found error again but don't be scared - the page is still there and all you need to do is go to 192.168.1.1/overview.sh and you will have a full functioning management page for that session in that browser.
The guys at Bitdefender have located the file that causes the forwards not to work and hopefully they will have a fix soon. Hope this helps someone.
Cheers