In most case, OWA 440 Login/Authentication Timeout error is related to the permission and Authentication. The following are some cases and resolutions.

Refer to How to reset/synchronize IUSR & IWAM passwords in both ADUC and IIS

Case 1: The IUSR_Servername and IWAM_servername accounts’ passwords were corrupted or has been changed and out of synchronizing between AD & IIS. Reset these accounts’ passwords in both ADUC and IIS. Then run IISRESET to restart IIS.

Case 2: The OWA server may have difficulty to communicate with the DC. Adding the iusr_servername & iwam_servername to the OWA server local users group may help.

Case 3: You may receive this error after upgrading the system or update security patches. Enabling and disabling the Integrated Authentication in the IIS. Then run IISRESET.
In some cases you may have to recreate the virtual directories. You sould do this only after trying the fixes I have described above. to do this follow the steps in this link.

http://exchangeshare.wordpress.com/2008/07/16/how-to-recreate-owa-virtual-directory-exchange-2007/