To resolve this problem, apply hotfix 955151.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
955151
Description of the ISA Server 2006 hotfix package: July 6, 2008
After you apply this hotfix, the Outlook Web Access logon form displays the options for private computers and for public computers. This hotfix takes effect only when you use the default form that ISA Server 2006 provides.
The hotfix replaces the Usr_pcode.htm file with an updated version of this file. The Usr_pcode.htm file is located in the following folder:
ISA_Install_Dir\CookieAuthTemplates\ISA\HTML
Note ISA_Install_Dir is a placeholder for the installation folder of ISA Server 2006.
If you have customized the Usr_pcode.htm file, hotfix 955151 does not replace the file. Therefore, the RSA SecurID form does not display the options to specify whether the client computer is a public computer or a private computer. In this situation, you must restore the original Usr_pcode.htm file, apply the hotfix, and then re-customize the Usr_pcode.htm file.