I'm having a really strange caching issue with my web app's javascript files & no-one seems to be able to tell what it is.

The issue is that I have deleted a section of code in the JS file, yet it's still appearing in the browser, both IE and FF.
I have tried a number of solutions but nothing has worked. if anyone has any suggestions as to what the issue would be, I would appreciate it.

What I have tried:
Manually remove & re-add the file
Rollback the file to a previous version
Remove the file from the index.html and re-add it
Clear all cache in FF & IE
Disable firebug
Check the script is updated by manually accessing the file via the application URL & Firebug Script tab
Renaming the JS file
Renaming the index.html file
Cleaning/rebuilding/removing the project
Restarting the server & eclipse
Pointing the server to a different location
Removing & re-adding the Tomcat server
Ctrl + F5
Checking the URL path/classpath in Eclipse is correct
Removing all Temp Internet Files (including when all associated apps were closed)
Adding Pragma no-cache metadata tag to the index.html

I'm at a loss as to what could be causing it.