Puzzling internet/network problem

[dobsonl]

Evening All,

 

Been fighting with this all day now and its doing my head in!!! Luckily its only affecting my workstation

 

Windows 7 enterprise all patched up to date, no firewalls enabled (have checked windows firewall and SEP) can get internet access fine and access network servers but Dropbox won't connect (Machine has allow all rule on lightspeed and it worked prior to today) and when opening outlook it prompts for a username & password, this never used to happen and upon entering my domain credentials which are valid after 30seconds or so it opens up to my cached mailbox but working offline which cant be taken back online.

 

Has anybody got any ideas? I cant cope with another day of using OWA!