Here's what I found with the Startasuser.dll. If landesk was previously installed on a computer but is just not working, like a service is not running then on a reinstall you get the startasuser.dll failure in the log but the reinstall may still work.
If you manually try to register the dll file there is a error.
What I am assuming that the Dll file is already registered by the previous installation.
The answer to my reinstall Landesk failing is indicated in my reply to Frank.
1. There was a reboot pending on one
2. By deleteing all the windows\temp\ files that have to do with Landesk, worked on others that were failing.