When you attempt to install SBS 2008 UR 2 (960911) it may failwith error code 6BA "Windows Update encountered and unknown error". One of the actions SBS2008 Update Rollup 2 (UR2)  performs is to change the Integrated Windows authentication in the companyweb site from NTLM to Negotiate (Kerberos) to allow you to browse http://companyweb from the server after installing IE rollup 963027, IE8 or Windows 2008 SP 2.

More info: SBS blog