I downloadexchnage 2007 sp1 twice and get the same result. It fails when installing and event view says: the description for the event 4999 from source MSExchnage Common cannot be found. Either the component that raises this even is not installed on your local computer or the installation is corrupt. It passes all checks prior to installation

did you do a setup /pad /on:orgname first?You may need to rerun that command to prep your envionrment for Exchange 2007.Waht OS are you installing on?2003 or 2008? What Service Pack on the OS etc.SF - MCITP:EMA, MCTS: MOSS 2007, OCS 2007, Exchange 2007

I got it resolved:ran servermanagercmd -i RSA-ADDS to install AD toolsthen setup /prepareschemathen setup /p /on:"your domain name here"last was the mailbox role failed. U need to right click setup and choose vista sp1 mode in order for the mailbox role to install.