Rx4Defs clears out corrupts defs and temp files created by definitions and installs new definition which is packed into it.
It is good tool easy to use..just double click and it does its job. 
However if you want to run it on multiple computers at once you can try psexec to push it.

 Thanks!

However I just found out with dbvalidator.bat that the database is corrupt :(

Restoring the SQL database did not fix the problem so it must have been around for quite some time now.

Is ur SEPM Database updated if not what is the error displaying while running the LUALL manually??
The Error no is really neccessary to fix it. LU has several causes to fail.

That virus definitions is not updating can of course be many things however if you database is corrupt you have to deal with that anyway. Restoring the database did not work actually it still failed dbvalidator check.

We practiced the documentation of "Disaster recovery for SEP" and reinstalled the server. Since we had a backup of certificate and domain name with all the passwords all clients added themselves automatically.

However we had to import all policies and settings and recreate all other settings to the same as before.

The whole operation took a couple of hours but we now have full connectivity with all our 2000 clients and virus definition is working :)

We installed MR5 on the SEP Manager and will migrate clients within the next couple of weeks.