"download" directory permissions keep changing

[ttorrey]

I offer MP3 downloads in addition to other products. I followed the osCommerce manual and set the permissions on the "download" directory to 755. However, when several customers have purchased downloads (which is not often), they email me telling me that they cannot access the file. I then check the permissions on the "download" directory and they seem to have changed to 644. I reset them to 755 and this enables the download. The problem is that this is happening frequently -- something is causing the directory permissions to change. Any ideas as to what???

 

Thanks