(working along and continuing to try different things) I have also just downloaded and installed the latest version of the OptionTree plugin. Still no luck.
I am more than happy to work with you step by step with config file settings and so forth; my site is currently in early days and I *really* like this theme (I would say I love it, but having a close friend from Finland broke me of the casual use of that word LOL). The features including typography and high degree of available customization make it a perfect fit for the type of news-magazine site that I'm trying to create...and the theme I am currently using (ProMax) is the best available of poor second-place choices.
Could this perhaps be related to some sort of broken scripting on the automatic installation process (which is handled through the Plesk control panel)? I realize as I consider this that I should not have claimed a "clean" install as I cannot be 100% certain that this is the case! As far as I can tell - keeping in mind that I am a rusty ASP/ASPX programmer and not a PHP programmer - it does nothing out of the ordinary except automate the creation of a database and insertion of necessary account variables in configuration files (e.g. db username and pw). (Again, this is a matter of personal convenience/ease of use; I'm far more familiar with MSSQL than MySQL.)
I will also be more than happy to communicate any issue resolution to my hosts, should we find that their install coding is the root of the problem. Anything I can do to facilitate the greater use of your wonderful theme, I am happy to do...if we can get it working :)
Best regards,
-jh