Log In impossible in I.E. and Safari

Hi, Strange issue. The cms works fine in chrome, on mac and on pc, but unable to get passed the login screen on safari and i.e.

(enter username and password and submit it just returns you to the login screen with no error message and the fields are blank).

I don't know if there has been any changes to host as thats controlled by my client (they use the crappy 1and1 in the UK (US servers)).

heres some details cmsb version: 2.0.3

Operating System Linux infong 2.4 #1 SMP Wed May 15 13:26:15 CEST 2013 i686 GNU/Linux Web Server Apache Database Server MySQL v5.1.71 (Max Connections: 18) PHP Version PHP v4.4.9 - phpinfo >>  Disk Space Free: 242.12 GB,  Total: 976.43 GB Server Resource Limits CPU Time: 10 seconds,  Memory Limit: unlimited,  Processes: 12 - ulimit >>