Tips & tricks:   |1| When using Mozilla Firefox check your browser settings under "Extras > Settings" regarding
  - Main (Settings Java und Javascript) 
  - Security 
  - Privacy
 
 
 Ascertain that the checkboxes Javascript, Java and "Load images automatically"have been activated.  
 |2| It is possible that cookies cause a concurrent logout during the login-process. In that case clear your cache and cookies.
 - Mozilla Firefox: Extras > Settings -> Private data button "Einstellungen", click the checkboxes "Cache" and "Cookies", click "OK" and  "Clear now", subsequently. Confirm with okay "OK". 
    
 - Internet Explorer: Extra > Internet settings > Main > clear cookies.
 
 
  |3| Problematic could also be several "Plug-ins" (which possibly installed themselves). It might be that there is a plug-in that causes after a very short time the site to refresh again, which finally ask for a relogin. In that case, please check your list of plug-ins. 
   |4| Another, possible, but not imperative origin of the problem might be the firewall, that you are probably using. A delicately one could be e.g.  "Zonealarm", when it was set strongly. 
 
  |