We ran into the following error when trying to install VMWare Server 2.0 - on Windows Server 2003.
"Error 1718. File was rejected by digital signature policy"
There is a hotfix available to resolve the issue from Microsoft. More information about the hotfix and the download can be found at http://support.microsoft.com/kb/925336.
The hotfix resolved the issue for us.
Dave
Ontrack Data Recovery