Due to problems with CAS on our exchange server i followed instructions on uninstalling a reinstalling the CAS roles onto exchange 2007. the uninstall went through fine but when trying to reinstall them the setup fails.Installing product D:\exchangeserver.msi failed. Fatal error during installation. Error code is 1603. Last error reported by the MSI package is 'The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2920After much investigation it apprears that due to updates up to and including roll up 9 being installed it will not allow me to install the roles back on.to uninstall all updates and reboot between each is going to be a long winded process and cause down time. does anyone know a way around this please as im baffled that i cant just install the CAS back onto the server.FYI the server is a dedicated exchange server on server 2008 standard.Thank you for your time.

Since you have other roles that remain installed, use Programs and Features (Windows 2008) in the Control Panel to add the CAS role. Double-click Microsoft Exchange Server 2007. This will launch Exchange Server setup in maintenance Mode and allow for adding roles.MCTS: Messaging | MCSE: S+M | Small Business Specialist

Hi,Which instructions did you follow to uninstall the CAS role on exchange server?And How to Modify an Exchange Installationhttp://technet.microsoft.com/en-us/library/bb124273.aspxDid you follow this one?Frank Wang

Have you seen below article. it talks about how to reinstall CAS role. You will also have to uninstall and reinstall IIS http://support.microsoft.com/kb/320202Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Thank you for your responseMy concern here is that i will have to reinstall exchange 2007, was hoping to not have to do this. If this is the only way i will give it a go this weekend.

Thank you for your responseI had not seen this document. Will have a good look through this and attempt this over the weekend.Thank you

Thank you for your replyI have tries this both from the programs and features and via the shell. it copies the files then errors with the mentioned error.

Hi,If you want to still reinstall the exchange 2007 sp1, I think you have to reboot the server.Have a look at this post: http://www.tech-archive.net/Archive/Exchange/microsoft.public.exchange.setup/2008-12/msg00010.htmlOr Could you try to download the SP2 and install it?Frank Wang