Exchange - Thanks for your answer.
I installed Exchange in two parts. First I installed from (network)drive z. I choosed the 4 Roles "Mailbox", "Hub Transport" "Client Access" and "UM".
That Installation crashed (I am not shure why - maybe because I had forgotton to install ASP.Net or because AD modification needed some more time because I didn't preparated it seperate.) However the Management tools had been installed.
I rebooted and remapped the installation drive "net use * \...". Windows choosed a different driveletter (w:).
I used "Add / remove software" to change my Exchange Installation (adding the 4 roles).
The installation Wizzard remebered drive z: for the installation files. I changed that to w: whitch worked fine for "Mailbox", "Hub Transport" "Client Access". But UM din't install because it was looking for a file from z:
After I corrected the path to the installaition files in 3 keys in the registry I could Install UM. One key was:
[HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionInstallerUserDataS-1-5-18Products461C2B4266EDEF444B864AD6D9E5B613InstallProperties]
So I had two crashes in the installation process but my question / bugreport is mainly concerning the installation stop whith UM.