I think there is a problem with the reparse points on the machines. You can query for the reparse points and delete them. After that try to install SEP.
There is a utility called "FSutil" which will help you in deleting the reparse points. You can find it from the below link,
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/fsutil_reparsepoint.mspx?mfr=true
Alternativley on Windows 7 you can use the following command to serach for the reparse points,
dir /AL /S