I thought moviesjukebox 2.5.1 has resolved this issue, but I still get movies not titled 'I' being placed under 'I', i.e. IMDB - Echelon Conspiracy, IMDB - Forgetting Sarah Marshall, etc.

I notice all of them are not given the proper ratings too. I suspect something wrong with the scans?

Can you upgrade to the latest version of YAMJ from http://mediaplayersite.com/, and then delete and rebuild your jukebox. This should fix the problems with IMDB in the title.
Don't forget to delete the lib and skins directories before unzipping the new version over the top of the old installation.
Andy