Size Issue when accessing listed files

I am using Drupal 6.13 with Filebrowser 6.x-2.0-rc10. I have successfully installed the module and it works fine for files <= 6 MB. I am using drupal for my company's intranet site and I need a file manager that allows large PDF's. The largest that we have is just over 20MB. As far as I know the PHP limit is 65 MB, so the implementation should work. I have allowed file uploads up to 65 MB and a total upload size of 150 MB thinking it may be a core setting. I have not found an option to change a maximum download file size within drupal. All efforts to resolve the issue have been unsuccessful. I am attaching a screen shot of the error message that adobe 7 professional displays when I try to open from the site or save, then open a file larger than 6 MB. When I download a file over 6 MB and save it to my desktop, the file size is about 270 KB. Something is happening to files larger than 6 MB when they are downloaded through Filebrowser. If I access the files by mapped drive directly to the folder that I am using for the upload it works wonderfully. So, the files are getting uploaded properly.

Is there a work around patch or a drupal core setting that I can change to resolve this issue?

Thank you for any assistance,

Newton