SBS 2008 - Installation didn't complete

Hello everybody,

I'm migrating from SBS 2003 to SBS 2008. Everything worked fine (even the AD replication) but at the end of the SBS installation, something went wrong and the SBS installation wizard crashed. I think may be the antivirus has been automatically deployed by GPO made the wizard crash.

Now, the server "seems" ok. But:
- everytime I login, I have a help message from windows telling me that teh installation didn't complete properly and that I have to repair the installation (when I read the detail of the MS msg, it tells me to make a complete reinstall...)
- Exchange 2007 wasn't installed so I installed it manually
- OWA directory is not showing, so OWA doesn't work...

How can I repair this SBS installation ?

Do you think I should restart the installation (but how ? This serve has already all the FSMO roles...)

Thanks !