.msi install fails silently

Trying to install 5.3.7 on Vista.

Installer fails with no error message.

Have tried to run .msi file from a command prompt opened as administrator (account I’m trying to install from is also an administrator account), and get error “access is denied”.

Don’t think .msi is corrupt as I can expand it fine with 7zip (but can’t find a setup or install file to try and run manually).

Get the same error when trying to install the help pack. Have checked that I have space and that the windows/temp folder is writeable.

Is there a way round this? Is there an older version with a different installer?

thanks

Sorry, have found the issue that was stopping this. Needed to right click on file, select Properties, and then there’s a button down the bottom which says “Unblock”. Now it seems to be working.