JS file taking 9 hours to update?

Hello.
See, I have a problem with my site, I think there's something wrong serverside.
I have a site and it uses a .js file to format the menu. However, whenever I update this file, it takes between 6 to 48 hours to update, whereas the rest of the files are updated automatically.
I've tried calling the file from explorer to see what it comes up with when I update, and it shows the older version.

However....if I log in into ftp and I check the file that is there, it is the newer version I uploaded.
Please, don't tell me to clean the cache, I know that isn't the problem. Other peeps are having the same problem viewing my site, plus, if it was a cache problem, the older version wouldn't show up when I specifically call it from internet explorer.
I'd like to know what's going on and why this file takes this long to update and if it it the server problem. why it keeps serving the old version of it and how it can be fixed.

At this time, 5 pm EST, my site is displaying an outdated version of the menu I uploaded 9 hours ago.

 

 

 

 

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