even with the latest Lazarus, bencos fails on Vista and Windows 7. I did a search installing older version and from the first one (BENCOS_20061223.exe) to BENCOS_20070430.exe, they all run perfectly. Starting BENCOS_20070505.exe, I get a popup "A reference was returned from the server." and it fails. I'll try to make a new project file and copy / paste the code. I think my project file is corrupt or have bad settings, but they look good to me. I compiled an empty project and it ran perfectly.
in the meantime you can grab the latest binaries here:
http://sites.google.com/a/detritus.qc.ca/realanime/
stay tuned!