virtualbox.org

I tried to upgrade VB 2.2.0 to 2.2.4 on my vista host but the installation is aborted after a rollback. Also deinstallation of the current version do not work probably. Here the rollback is processed too. These rollbacks occur before I could select an administrator repair.
Can anybody tell me how to fix this?

As an additional bonus the NAT networking doesn´t work anymore since these operations. Maybe bridged networking will, but I don´t
try till now.

This ticket describes how to uninstall version 2.2.0 http://www.virtualbox.org/ticket/3701