Can't connect to admin.php

I installed vicidial last week and all switched it on yesterday. Calls were made and all seemed well. The server has a reboot 3am every day and today when agents tried to log on the saw a message
However when I simply browse to the serve address I see the standard apache page
Agents can still make calls from handsets and softphones and I still have ssh access.
Details of the installation are
Anyone have any ideas and bear in mind I'm still a beginner where Linux is concerned but know enough to know when to stop and ask for help - this is one of these cases!
. his happens when connecting to the admin login page and the client login page."Oops! Google Chrome could not connect to 192.168.x.x"
However when I simply browse to the serve address I see the standard apache page
"It Works!"
Agents can still make calls from handsets and softphones and I still have ssh access.
Details of the installation are
Dell Poweredge, 2 x 1Tb HDD, 4Gb RAM, vicibox 5.0.3, no additional software and I have read the manager and agent manual (paid versions in both cases]
Anyone have any ideas and bear in mind I'm still a beginner where Linux is concerned but know enough to know when to stop and ask for help - this is one of these cases!