Ok i had a similiar problem like this with oscmax 1.7. But what it turned it to be was i had the setting wrong for the large files folder and the thumbnails etc. I'm certain its not a coding thing, also certain you need not to reinstall oscmax. you have to check you setting in the admin CP and your directory paths in your configuration file. ALso any files you put into the large images directory have to have a prefix or suffix so that they can be recognized. This is me talking from my 1.7 debacals.