Repair / reinstall exchange cas role :
http://technet.microsoft.com/en-us/library/dd767439%28WS.10%29.aspxWindows SBS 2008 Repair guide :
http://technet.microsoft.com/en-us/library/dd430085%28WS.10%29.aspx
http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Server/SBS_Small_Business_Server/Q_24255654.html
Hi Junzcpt, I would suggest to go through the first link and follow it to repair ; also the repair guide is a good reference ;
Make sure you have a backup for your mailboxes etc ; Once you have that then do this repair according to the first link
Create a notepad file with your tasks list on a seperate computer so you are sure what you have to do next.
Hope this helps
I will post back soon